Phd Thesis Nshiers

ACOUSTIC DESIGN FOR INPATIENT

FACILITIES IN HOSPITALS

Thesis submitted in partial fulfilment of the requirements of

London South Bank University for the degree of

Doctor of Philosophy

By

Nicola Jane Shiers

Supervisor: Professor B.M. Shield, London South Bank University

Second Supervisor: Rosemary Glanville, London South Bank University

December 2011

Acoustic Design for Inpatient Facilities in Hospitals Table of Contents

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i

Table of Contents

LIST OF FIGURES ………………………………………………………………………………. viii

LISTOF TABLES …………………………………………………………………………………. xiii

Acknowledgements ………………………………………………………………………………. xv

Acoustic glossary and definitions ……………………………………………………………… xvi

Chapter 1 Introduction …………………………………………………………………….. 2

Chapter 2 Acoustic standards and guidance ……………………………………………. 5

2.1 Introduction …………………………………………………………………….. 5

2.2 UK design guidance ………………………………………………………….. 5

2.2.1 HTM 08-01 …….…………………………………………………...... 6

2.3 European healthcare design guidance ……………………………………… 10

2.4 World Health Organisation guidelines ………………………………………. 11

2.5 Control of infection ……………………………………………………………. 12

2.5.1 HTM 60 ……………………………………………………………….. 12

2.5.2 National Standards of Cleanliness for the NHS…………….......... 13

2.5.3 HFN 30 Infection Control in the built environment ……………….. 14

2.6 Discussion ……………………………………………………………………... 14

2.7 Conclusions ……………………………………………………………………. 15

Chapter 3 Previous research on hospital noise ………………………………………… 16

3.1 Introduction …………………………………………………………………….. 16

3.2 Noise measurement studies …………………………………………………. 16

3.2.1 Limitations of noise measurement studies ……………………....... 18

3.2.2 Understanding the overall hospital noise climate ………………... 21

3.2.3 Identifying noise sources ………………………………………….... 22

3.2.4 Discussion ………………………………………………………….... 23

3.3 Sleep studies ………………………………………………………………….. 23

3.3.1 Modification of room acoustics and its effects on sleep …………. 24

3.3.2 Discussion …………………………………………………………… 25

3.4 The effects of behaviour modification on hospital noise ………………….. 25

3.4.1 Discussion ……………………………………………………………. 26

3.5 The effects of room acoustic design modifications ………………………… 27

3.5.1 Control of infection and room acoustics ………………………….. 27

3.5.2 Physiological response to acoustic modification …………........... 28

3.5.3 Discussion ………………………………………………………….... 29

3.6 Conclusions …………………………………………………………………..... 29

Chapter 4 The effects of noise on staff and patients …………………………………. 30


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4.1 Introduction ……………………………………………..………………………. 30

4.2 Effects of noise on staff ……………………………………………………….. 30

4.2.1 Stress levels and burnout …………………………………………… 30

4.2.2 Cognitive function / memory ………………………………………… 30

4.2.3 Effects of acoustic design on the work environment …………...... 31

4.2.4 Discussion ……………………………………………………………. 31

4.3 Effects of noise on patients ………………………………………………….. 32

4.3.1 Recovery rates ……………………………………………………… 32

4.3.2 Subjective response to noise ………………………………………. 32

4.3.3 Speech privacy ………………………………………………………. 33

4.3.4 Single bed patient rooms …………………………………………… 33

4.3.5 Discussion ……………………………………………………………. 33

4.4 Conclusions …………………………………………………………………….. 34

Chapter 5 Study design ………………………………………………………………...… 35

5.1 Introduction ……………………………………………………………………. 35

5.2 Study outline – aims and objectives ………………………………………… 35

5.2.1 Acoustic survey ……………………………………………………… 36

5.2.2 Questionnaire surveys ……………………………………………… 36

5.2.3 Comparison studies ………………………………………………… 37

5.3 Acoustic survey methodology ………………………………………………. 38

5.3.1 Equipment ……………………………………………………………. 38

5.3.2 Control of Infection ………………………………………………….. 38

5.3.3 Acoustic parameters ………………………………………………… 39

5.3.4 Presentation of sound levels ……………………………………….. 39

5.3.5 Measurement interval ……………………………………………….. 39

5.3.6 Measurement locations …………………………………………….. 39

5.3.7 Identifying sources of high level noise without an observer …….. 40

5.3.8 Reverberation times ………………………………………………….. 40

5.4 Questionnaire survey design ……………………………………………….. 40

5.4.1 Staff questionnaires …………………………………………………. 41

5.4.2 Patient questionnaires ………………………………………………. 41

5.5 Preliminary work ……………………………………………………………… 42

5.5.1 Building relationships with hospitals and Healthcare Trusts …….. 42

5.5.2 Ethics and Trust approval …………………………………………… 43

5.6 Conclusions …………………………………………………………………….. 44

Chapter 6 Pilot study ……………………………………...……………………………….. 45

6.1 Introduction ……………………………………………………………………... 45

6.2 Background …………………………………………………………………….. 45

6.3 Sky Ward ……………………………………………………………………….. 46

6.4 Building acoustic design considerations …………………………………….. 47

6.4.1 Nurse stations and common areas ………………………………… 47

6.4.2 Patient accommodation ……………………………………………… 47


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6.5 Ward routines ……………………………………………………………………48

6.5.1 Staffing and patient levels …………………………………………… 48

6.5.2 Staff shift patterns and ward rounds ……………………………….. 49

6.5.3 Cleaning ……………………………………………………………….. 49

6.5.4 Meal times …………………………………………………………….. 49

6.5.5 Medical equipment with alarms …………………………………….. 49

6.5.6 Access to patient accommodation …………………………………. 49

6.6 Measurement locations ……………………………………………………….. 50

6.6.1 Nurse stations ………………………………………………………… 50

6.6.2 Four bed bays ………………………………………………………… 53

6.6.3 Single patient rooms …………………………………………………. 55

6.7 Equipment and microphone positioning ……………………………………... 56

6.7.1 Nurse stations ………………………………………………………… 57

6.7.2 Four bed bays ………………………………………………………… 57


6.8 Other considerations ……………………………………………………………58

6.8.1 Identifying the optimal ‘level above’ setting for trigger files ……… 58

6.8.2 Publicising the study …………………………………………………. 59

6.8.3 Reverberation times ………………………………………………….. 59

6.9 Questionnaire survey considerations ………………………………………… 60

6.10 Overall acoustic survey results ……………………………………………….. 60

6.11 Nurse stations ………………………………………………………………….. 62

6.11.1 Sources of high level noise …………………………………………. 63

6.12 Four bed bays ………………………………………………………………….. 66


6.13 Single patient rooms …………………………………………………………… 69


6.14 Establishing a representative measurement interval ……………………… 71

6.15 Other measured acoustic parameters ………………………………………. 73

6.15.1 Reverberation times …………………………………………………. 73

6.15.2 Ambient noise levels ………………………………………………… 74

6.16 Results of the staff questionnaire surveys ……………….…………………. 75

6.16.1 Staff profile ……………………………………………………………. 75

6.16.2 Noise annoyance and interference ………………………………… 75

6.16.3 Important sounds …………………………………………………….. 78

6.17 Patient questionnaires …………………………………………………………. 79

6.17.1 Parent / patient profile ……………………………………………….. 79

6.17.2 Noise annoyance …………………………………………………….. 80

6.17.3 Positive sounds ………………………………………………………. 82

6.17.4 Privacy and ease of hearing ………………………………………… 83

6.17.5 Patient’s questionnaire comments …………………………………. 83

6.18 Summary of results ………………………………………………………….. 83

6.19 Follow up discussions ………………………………………………………… 84

6.20 Conclusions ……………………………………………………………………. 87


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Chapter 7 Bedford Hospital …………………………………………………….…………. 91

7.1 Introduction ……………………………………………………………………... 91

7.2 Background …………………………………………………………………….. 91

7.3 Building acoustic design considerations ……………………………………. 92

7.4 Hospital policies and equipment common to both wards ………………… 92

7.4.1 Meal times …………………………………………………………… 92

7.4.2 Ward design …………………………………………………………. 93

7.4.3 Occupancy levels …………………………………………………… 94

7.4.4 Shift patterns ………………………………………………………… 94

7.4.5 Visiting hours ………………………………………………………… 94

7.4.6 Ward access …………………………………………………………. 94

7.4.7 Access to patient accommodation ………………………………… 94

7.4.8 Cleaning staff ………………………………………………………… 94

7.4.9 Mobile phone policy …………………………………………………. 94

7.4.10 Entertainment systems ……………………………………………… 95

7.4.11 Rubbish bins ………………………………………………………….. 95

7.4.12 Staff call ……………………………………………………………….. 95

7.4.13 Medical equipment alarms ………………………………………….. 95

7.4.14 Trolleys ………………………………………………………………... 95

7.4.15 Internal telephones …………………………………………………… 95

7.4.16 Hand gels ……………………………………………………………… 95

7.5 Medical ward ……………………………………………………………………. 96

7.5.1 Ward specific information ……………………………………………. 98

7.6 Medical ward overall noise survey results ……………………………………100

7.6.1 Nurse station and ward entrance …………………………………… 101

7.6.2 Multi-bed bays ………………………………………………………… 103


7.6.4 Further analysis of high level noise sources ………………………. 106

7.7 Surgical ward …………………………………………………………………… 109

7.7.1 Ward specific information ……………………………………………. 109

7.8 Surgical ward overall noise survey results ………………………………….. 112

7.8.1 Nurse station ……………………..…………………………………… 113

7.8.2 Multi-bed bays ………………………………………………………… 115


7.8.4 Further analysis of high level noise sources ………………………. 118

7.9 Results of the staff questionnaire surveys ….………………………........... 120

7.9.1 Staff profile ……………………………………………………………. 120

7.9.2 Noise annoyance …………………………………………………….. 121

7.9.3 Interference with work ………………………………………………. 124


7.10 Results of the patient questionnaire surveys ……………………………….. 126

7.10.1 Patient profiles.………………………………………………………... 126

7.10.2 Noise annoyance and disturbance …………………………………. 127

7.10.3 Positive sounds ……..………………………………………………... 131

7.10.4 Ease of hearing and privacy ………………………………………... 132

7.11 Questionnaire comments …………………………………………………….. 132


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7.12 Summary ………………………………………………………………………. 132

7.13 Conclusions ……………………………………………………………………. 133

Chapter 8 Ceiling intervention study, Bedford Hospital ………………………………. 135

8.1 Introduction …………………………………………………………………….. 135

8.2 Bay information ………………………………………………………………… 136

8.3 Effect of ceiling tile change on noise levels …………………………………. 137

8.4 Effect of ceiling tile change on reverberation time ………………………….. 140

8.4.1 Unoccupied reverberation times ……………………………………. 140

8.4.2 Occupied reverberation times ………………………………………. 141

8.5 Comparison of unoccupied and occupied RTs …………………………….. 142

8.6 Conclusions …………………………………………………………………….. 143

Chapter 9 Addenbrooke’s Hospital .......……………………………………………......... 144

9.1 Introduction …………………………………………………………………….. 144

9.2 Background …………………………………………………………………….. 144

9.3 Ward D8 (surgical) …………………………………………………………….. 145

9.3.1 Building design ………………………………………………………. 145

9.3.2 Ward layout …………………………………………………………… 146

9.3.3 Ward specific information …………………………………………… 146

9.3.4 Managing the study ………………………………………………….. 148

9.4 Overall noise survey results Ward D8 ……………………………………… 151

9.4.1 Nurse station …………………………………………………………. 152

9.4.2 Multi-bed bays ……………………………………………………….. 154

9.4.3 Further analysis of high level noise sources ……………………… 155

9.4.4 Representative measurement interval …………………………….. 158

9.5 Ward N3 (medical) ……………………………………………………………. 160

9.5.1 Building design ………………………………………………………. 160

9.5.2 Ward layout …………………………………………………………… 160



9.6 Overall noise survey results Ward N3 ……………………………………….. 166

9.6.1 Nurse station …………………………………………………………. 167

9.6.2 Multi-bed bays ……………………………………………………….. 170

9.6.3 Single patient rooms ………………………………………………… 171


9.7 Ward M4 (surgical) …………………………………………………………….. 174

9.7.1 Building construction …………..…………………………………….. 174

9.7.2 Ward layout …………………………………………………………… 174



9.8 Overall noise survey results Ward M4 ……………………………………….. 181

9.8.1 Nurse station …………………………………………………………. 182

9.8.2 Multi-bed bays ……………………………………………………….. 184

9.8.3 Single patient rooms ………………………………………………… 185


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9.9 Results of the staff questionnaire surveys ….………………………........... 188

9.9.1 Staff profile ……………………………………………………………. 188

9.9.2 Noise annoyance …………………………………………………….. 189

9.9.3 Interference with work ……………………………………………….. 190


9.10 Results of the patient questionnaire surveys ……………………………….. 193

9.10.1 Patient profiles.……………………………………………………….. 193

9.10.2 Noise annoyance and disturbance ………………………………… 194

9.10.3 Positive sounds ……..……………………………………………….. 198

9.10.4 Ease of hearing and privacy ………………………………………… 199

9.11 Questionnaire comments …………………………………………………….. 199

9.12 Summary ………………………………………………………………………. 199

9.13 Conclusions ……………………………………………………………………. 201

Chapter 10 Blind estimation of reverberation time ………………………………………. 202

10.1 Introduction …………………………………………………………………….. 202

10.2 Initial validation ………………………………………………………………… 202

10.3 Validation using real and simulated measurements ………………………. 203

10.3.1 Validation 1 …………………………………………………………… 204

10.3.2 Validation 2 …………………………………………………………… 205

10.3.3 Validation study conclusions ………………………………………… 207

10.4 Estimation of RT in occupied hospital wards ……………………………….. 208

10.4.1 Methodology ………………………………………………………….. 208

10.4.2 MLE-RT20 estimates from day time data …………………………... 209

10.5 Comparison of day and night time MLE-RT20 estimates …………………… 212

10.6 Summary ………………………………………………………………………. 214

10.7 Conclusions …………………………………………………………………… 215

Chapter 11 Analysis of objective and subjective data …………………………………… 216

11.1 Introduction ……………………………………………………………………... 216

11.2 Factors affecting noise levels ……………………………………………… 216

11.2.1 Effect of bay size ……………………………………………………… 216

11.2.2 Surgical and medical wards ………………………………………… 219

11.2.3 Impact of high level noise events on overall noise levels …………220

11.2.4 Noise levels and reverberation times ………………………………. 221

11.3 Factors affecting patient perceptions of noise ……………………………. 222

11.3.1 Overall ………………………………………………………………… 222

11.3.2 Patient gender ……………………………………………………….. 224

11.3.3 Age ……………………………………………………………………. 225

11.3.4 Hearing impairment …………………………………………………. 226

11.3.5 Length of stay ……………………………………………………….. 227

11.3.6 Bed position ………………………………………………………….. 229

11.3.7 Speech intelligibility and privacy …………………………………… 230


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11.4 Factors affecting staff perceptions of noise ………………………………… 231

11.4.1 Overall ………………………………………………………………… 231

11.4.2 Staff gender …………………………………………………………… 231

11.4.3 Age …………………………………………………………………….. 232

11.4.4 Time worked on the ward …………………………………………… 233

11.4.5 Time worked at the hospital ………………………………………… 233

11.4.6 Relationship between noise annoyance and noise interference … 234

11.5 Discussion ………………………………………………………………………. 234

11.6 Conclusions …………………………………………………………………… 236

Chapter 12 Noise control in inpatient care …..…………………………………………… 237

12.1 Introduction …………………………………………………………………….. 237

12.2 Optimising the acoustic design of the ward ………..……………………….. 237

12.2.1 Design for infection control ………………………………………… 237

12.2.2 The effects of adding acoustic absorbency………..……………… 238

12.2.3 Ward design …………………………………………………………. 238

12.2.4 Building construction ……………………………………………….. 239

12.2.5 Building age and overall noise levels ……………………………... 240

12.3 Ward equipment ….……….…………………………………………………. 242

12.3.1 Nurse call systems …………………………………………………… 242

12.3.2 Internal telephones …………………………………………………… 242

12.3.3 Medical equipment alarms ………………………………………….. 243

12.3.4 Doorbell ……………………………………………………………….. 244

12.3.5 Rubbish bins ………………………………………………………….. 244

12.3.6 Ward furniture ………………………………………………………… 244

12.3.7 Wheeled equipment ………………………………………………….. 244

12.3.8 Ring binders …………………………………………………………... 245

12.3.9 Doors …………………………………………………………………... 245

12.4 Human behaviour ……………………………………………………………… 245

12.5 WHO guidelines ………………………………………………………………. 247

12.6 Acoustic parameters …………………………………………………………. 247

12.7 Conclusions …………………………………………………………………… 248

Chapter 13 Conclusions ……………………………………………………………………. 249

13.1 Introduction …………………………………………………………………….. 249

13.2 Overall conclusions ….………………………………………………………. 249

13.2.1 Building design ……………………………………………………….. 249

13.2.2 Patient accommodation ……………………………………………… 250

13.2.3 Staff and patient perceptions ……………………………………….. 250

13.2.4 Ward equipment ……………………………………………………… 250

13.2.5 Human behaviour …………………………………………………….. 251

13.2.6 Guidelines …………………………………………………………….. 251

13.3 Recommendations ………………..………………………………………….. 251

13.4 Further work …………………………………………………………………… 252

References ……………………….……………………………………………………………….. 253

Acoustic Design for Inpatient Facilities in Hospitals List of Figures

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LIST OF FIGURES

Figure 2.1 Recommended RTs for different room functions and volumes, HTM 2045 (NHS Estates, 1996) 9

Figure 3.1 LAeq values measured in hospitals during day time hours as a function of

the year of study publication. (Busch-Vishinac et al, 2005) 17

Figure 3.2 LAeq values measured in hospitals during night time hours as a function of

the year of study publication. (Busch-Vishinac et al, 2005) 17

Figure 5.1 Sound level meter, environmental case and associated equipment 38

Figure 6.1 The Octav Botnar Wing 46

Figure 6.2 Main entrance to the Octav Botnar Wing 46

Figure 6.3 Sky Ward Reception 47

Figure 6.4 Typical four bed bay 47

Figure 6.5 Ultima ceiling tile sound absorption coefficients (α) over a range of frequencies 48

Figure 6.6 Layout of Sky Ward with microphone positions 51

Figure 6.7 Nurse Station 1 50

Figure 6.8 Internal corridor 50

Figure 6.9 Internal telephone & security monitor 52

Figure 6.10 Wall mounted speaker grill 52

Figure 6.11 Nurse station 2 53

Figure 6.12 Nurse station 2 desk 53

Figure 6.13 4-bed bay B 54

Figure 6.14 Hand washing sink, door to shower room and lockers 54

Figure 6.15 Patient bed and fold down chair 54

Figure 6.16 Ward entrance with rubbish bins 54

Figure 6.17 Patient bed showing bed head services 55

Figure 6.18 Locked door onto balcony 55

Figure 6.19 Door to ensuite, pull down bed, sink and rubbish bins 55

Figure 6.20 Patient bed and opening windows 56

Figure 6.21 Rubbish bins and hand washing sink 56

Figure 6.22 Pull down bed 56

Figure 6.23 Flat screen television 56

Figure 6.24 Microphone position at nurse station 1 57

Figure 6.25 Microphone position at nurse station 2 57

Figure 6.26 4-bed bay B with microphone placed on top of lockers 58

Figure 6.27 Single patient room 1 with microphone position shown 58

Figure 6.28 Single patient room 2 with microphone position shown 58

Figure 6.29 Average day and night LAeq levels measured at each location 62

Figure 6.30 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse stations 63

Figure 6.31 Nurse call console 64

Figure 6.32 The number and levels (LAmax) of occurrences of the nurse call system

at nurse station 1, measured at 3 m over 5 days 64

Figure 6.33 The number and levels (LAmax) of occurrences of the ward doorbell at

nurse station 2, measured at 3 m over 19 hours 65

Figure 6.34 Average LAmax of the nurse call system, internal telephone and ward doorbell 66

Figure 6.35 Average LAeq,1hr and LA90,1hr levels over 24 hours for 4-bed bays A and B 67

Figure 6.36 Percentages of high level noise events by type measured in 4-bed bays A and B 68


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Figure 6.37 Average LAeq,1hr and LA90,1hr levels over 24 hours for single patient rooms

A and B 69

Figure 6.38 Percentages of high level noise events by type for single patient rooms

A & B 70

Figure 6.39 LAeq,1hr levels measured over five consecutive days at nurse station 1 72

Figure 6.40 Average LAeq,1hr levels over 24 hours for week 1 and week 2 at nurse station 1 72

Figure 6.41 Distribution of the extent of staff annoyance 76

Figure 6.42 Percentage of staff rating an annoyance noise event with a 2, 3 or 4 76

Figure 6.43 Distribution of the extent of noise interference with work 77

Figure 6.44 Percentage of staff rating an interference noise event with a 2, 3 or 4 78

Figure 6.45 Mean importance rating of certain noise events 79

Figure 6.46 Parents by age bracket 79

Figure 6.47 Patients by age bracket 79

Figure 6.48 Distribution of the extent of parent / patient annoyance during the day time 80

Figure 6.49 Percentage of parents / patients rating an annoyance noise event with a 2, 3 or 4 81

Figure 6.50 Distribution of the extent of parent / patient disturbance during the night time 81

Figure 6.51 Percentage of parents / patients rating a disturbance noise event with a 2, 3 or 4 82

Figure 7.1 Original building, Bedford Hospital (1803) 91

Figure 7.2 Five storey ward block 92

Figure 7.3 Main hospital entrance 92

Figure 7.4 Medical ward kitchen 93

Figure 7.5 Hospicom entertainment console 96

Figure 7.6 Automatic hand gel dispenser 96

Figure 7.7 Single patient room 96

Figure 7.8 Microphone suspended from ceiling 97

Figure 7.9 Microphone on tripod 97

Figure 7.10 Detailed plan of the medical ward showing microphone positions 99


Figure 7.12 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station

and ward entrance 102

Figure 7.13 LAmax,2s and LAeq,2s fluctuating over a ten minute interval at the nurse station 102

Figure 7.14 Average LAeq,1hr levels over 24 hours for the multi-bed bays 104

Figure 7.15 Average LA90,1hr levels over 24 hours for the multi-bed bays 104

Figure 7.16 Average LAeq,1hr levels over 24 hours for the single rooms 105

Figure 7.17 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a three

hour period in single room A 106

Figure 7.18 Average number of high level noise events recorded at each location per day 106

Figure 7.19 Average number of high level noise events recorded at each location per night 108

Figure 7.20 Detailed plan of the surgical ward showing microphone positions 111


Figure 7.22 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station 113

Figure 7.23 LAmax,2s (green trace) and LAeq,2s (red trace) measured over a thirty

minute interval during the night (2.40am onwards) at the nurse station 114

Figure 7.24 LAmax,2s and LAeq,2s fluctuating over a 11 minute interval at the nurse station 115

Figure 7.25 Average LAeq,1hr for each multi-bed bay and combined average LA90,1hr

level for all bays over 24 hours 116

Figure 7.26 Average LAeq and LA90 levels for single rooms A and B and multi-bed bays 117


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Figure 7.27 LAmax,2s (green trace) and LAeq,2s (red trace) showing the noise levels

due to a medical equipment alarm over a period of 13 minutes 118

Figure 7.28 Average number of high level noise events captured at each location per day 119

Figure 7.29 Average number of high level noise events captured at each location per night 120

Figure 7.30 Age of respondents by band 121

Figure 7.31 Time worked on the ward 121

Figure 7.32 Time worked at the hospital 121

Figure 7.33 Staff perception of noise in terms of annoyance 122

Figure 7.34 The percentage of staff rating an annoyance noise event with a 2, 3 or 4 123

Figure 7.35 Staff perception of the extent to which noise interferes with work 124

Figure 7.36 The percentages of staff rating an interference noise event with a 2, 3 or 4 124


Figure 7.38 Gender split by ward type 126

Figure 7.39 Patients age by band 126

Figure 7.40 Length of patient stay when completing the questionnaire 127

Figure 7.41 Patient perception of the day time ward noise environment 128

Figure 7.42 The percentage of patients rating an annoyance noise event with a 2, 3 or 4 129

Figure 7.43 Patient perception of the night time ward noise environment 130

Figure 7.44 The percentage of patients rating a disturbance noise event with a 2, 3 or 4 131

Figure 8.1 Photographs of the bay during refurbishment 135

Figure 8.2 Absorption coefficients of Armstrong Bioguard Plain ceiling tiles Source: Manufacturer’s product specification sheet 136

Figure 8.3 Absorption coefficients of Armstrong Bioguard Acoustic ceiling tiles Source: Manufacturer’s product specification sheet 136

Figure 8.4 Average LAeq,1hr levels over 24 hours pre and post ceiling change 138

Figure 8.5 Average number of trigger files recorded over 24 hours by event type 139

Figure 8.6 The frequency content of noise of metal cutlery 139

Figure 8.7 Source (S) and receiver (R) positions used to measure reverberation

time in the unoccupied bay before and after the ceiling change 140

Figure 8.8 Average unoccupied RT20 measurements with 95% confidence limits

(Impulse Response Method) 141

Figure 8.9 Occupied MLE-RT20 estimates pre and post the ceiling replacement 142

Figure 9.1 Original building, Addenbrooke’s Hospital 144

Figure 9.2 Detailed plan of ward D8 showing microphone positions 150



Figure 9.5 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a ten

minute interval at the nurse station during the night 153

Figure 9.6 Average LAeq,1hr levels over 24 hours for the multi-bed bays 155



Figure 9.9 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a 19 minute

interval at in the elderly trauma unit 158

Figure 9.10 Average LAeq,1hr levels over 24 hours for two non-consecutive weeks in

the 12-bed bay 159

Figure 9.11 Detailed plan of the ward N3 showing microphone positions 165




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interval at the nurse station during the afternoon 168

Figure 9.15 Frequency content of door bang at the nurse station 169

Figure 9.16 Average LAeq,1hr for each multi-bed bay and combined average LA90,1hr level

for all bays over 24 hours 170

Figure 9.17 Average LAeq,1hr levels over 24 hours for the single rooms 171



Figure 9.20 Percentage break down of high level noise events by type in 4-bed bay B 173

Figure 9.21 Plan of Ward M4 detailing shared areas and microphone positions 179

Figure 9.22 Detailed plan of Ward M4 showing study locations and microphone positions 180


Figure 9.24 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse stations 183


interval at the nurse station at 05.30 183

Figure 9.26 Average LAeq,1hr and LA90,1hr level for each multi-bed bay over 24 hours 184

Figure 9.27 Average LAeq,1hr and LA90,1hr levels over 24 hours for the single rooms 185



Figure 9.30 Age of respondents by band 188

Figure 9.31 Time worked on the ward 189

Figure 9.32 Time worked at the hospital 189

Figure 9.33 Staff perception of noise in terms of annoyance 189

Figure 9.34 The percentage of staff rating an annoyance noise event with a 2, 3 or 4 190

Figure 9.35 Staff perception of the extent to which noise interferes with work 191

Figure 9.36 The percentages of staff rating an interference noise event with a 2, 3 or 4 191


Figure 9.38 Gender split by ward type 193

Figure 9.39 Patients age by band 193

Figure 9.40 Length of patient stay when completing the questionnaire 194

Figure 9.41 Patient perception of the day time ward noise environment 195

Figure 9.42 The percentages of patients on Ward D8 rating an annoyance noise

event with a 2, 3 or 4 196

Figure 9.43 Patient perception of the night time ward noise environment 197

Figure 9.44 The percentages of patients rating a disturbance noise event with a 2, 3 or 4 198

Figure 10.1 Clinical skills laboratory used for validation 1 204

Figure 10.2 Average RT20 measurements with 95% confidence limits


Figure 10.3 Average RT20 measurements with 95% confidence limits


Figure 10.4 Accuracy of RT20 estimations in relation to actual measured values

Figure 10.5 MLE-RT20 estimates for five multi-bed bays in Ward D8, Addenbrooke’s

Hospital (day time data) with 95% confidence limits 210

Figure 10.6 MLE-RT20 estimates for six locations in Ward N3, Addenbrookes

Hospital (day time data) with 95% confidence limits 210

Figure 10.7 MLE-RT20 estimates for seven locations in the surgical ward,

Bedford Hospital (day time data) with 95% confidence limits 211


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Figure 10.8 Comparison of day and night time estimates, 7-bed bay, Ward D8,

Addenbrooke’s Hospital 212


Addenbrooke’s Hospital 213

Figure 10.10 Comparison of day and night time estimates, 4-bed bay,

medical ward, Bedford Hospital 213

Figure 11.1 Average day time levels by bay size for all main study wards 218

Figure 11.2 Average night time levels by bay size for all main study wards 218

Figure 11.3 Average day time noise levels and average number of day time high level

noise events for each bay 220

Figure 11.4 Average night time noise levels and average number of night time high

level noise events for each bay 221

Figure 11.5 Average day time noise levels and estimated reverberation times in each bay 222

Figure 11.6 Overall patient perception of the noise climate 223

Figure 11.7 Overall percentages of patient annoyed / disturbed by noise 223

Figure 11.8 Mean patient perception rating of noise by gender 224

Figure 11.9 Percentages of patients annoyed / disturbed by noise by gender 224

Figure 11.10 Mean rating of patient perceptions of day and night noise and age 225

Figure 11.11 Percentages of patients annoyed / disturbed and age 226

Figure 11.12 Percentage of hearing impaired by age group 226

Figure 11.13 Percentage of patients annoyed / disturbed with hearing impairment 227

Figure 11.14 Mean rating of patient perceptions of day and night noise and length of stay 228

Figure 11.15 Percentages of patients annoyed / disturbed and length of stay 228

Figure 11.16 Percentages of patients annoyed / disturbed and bed position 229

Figure 11.17 Patient privacy and bay size 230

Figure 11.18 Staff levels of annoyance and interference 231

Figure 11.19 Level of noise annoyance / interference by staff gender 232

Figure 11.20 Level of noise annoyance / interference by staff age 232

Figure 11.21 Level of noise annoyance / interference by time worked on the ward 232

Figure 11.22 Level of noise annoyance / interference by time worked at the hospital 234

Figure 12.1 Average day time levels by building age for all patient accommodation 241

Figure 12.2 Average night time levels by building age for all patient accommodation 241

Acoustic Design for Inpatient Facilities in Hospitals List of Tables

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xiii

LIST OF TABLES

Table 2.1 Example of criteria for intrusive noise from external sources, HTM 08-01

(The Stationary Office, 2008) 7

Table 2.2 Example of criteria for internal noise from mechanical and electrical

services, HTM 08-01 (The Stationary Office, 2008) 7

Table 2.3 Example of sound insulation parameters of rooms, HTM 08-01


Table 2.4 Example of sound insulation ratings (dB, DnT,w) to be achieved

on site, HTM 08-01 (The Stationary Office, 2008) 8

Table 2.5 Extract from Chapter 8 ‘Checklists’, HTM 08-01


Table 2.6 Standards and guidelines for healthcare design in Europe

(from Bergman and Janssen, 2008) 11

Table 2.7 Acoustic parameters (from Bergman and Janssen, 2008) 11

Table 2.8 World Health Organisation guidelines for hospital wards and treatment rooms 12

Table 2.9 Recommended ceiling characteristics for hospital room types, HTM 60

(NHS Estates, 2005) 13

Table 3.1 Measurement data from studies cited in Section 3.2 14

Table 6.1 Measurement location and time interval 60

Table 6.2 Average LAeq measured for 24 hour, day and night time periods at

each location 61

Table 6.3 Average and maximum noise levels of identified events in single room A 7 1

Table 6.4 Reverberation times measured in different ward accommodation 74

Table 6.5 Ambient noise levels measured in unoccupied patient accommodation 74

Table 7.1 Medical ward - measurement locations, time periods and patient gender 100


each location 100

Table 7.3 Examples of noise events at the nurse station 103

Table 7.4 Examples of noise sources and levels on the medical ward 108

Table 7.5 Measurement location, time periods and patient gender type 112

Table 7.6 Average LAeq for 24 hour, day and night time periods at each location 112

Table 8.1 Average LAeq measured during the day and night time pre and post

the ceiling change 138

Table 8.2 Reverberation times for both the unoccupied and occupied bay

pre ceiling change 1 43

Table 8.3 Reverberation times estimates for both the unoccupied and occupied

bay post ceiling change 143

Table 9.1 Ward D8 - measurement locations, time periods and patient gender 151


each location 151


Table 9.4 Examples of noise events in the multi-bed bays 158

Table 9.5 Measurement location, time interval and patient type 166

Table 9.6 Average LAeq measured for 24 hour, day and night time periods

at each location 166


Acoustic Design for Inpatient Facilities in Hospitals List of Tables

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xiv

Table 9.8 Measurement location, time interval and patient gender 181

Table 9.9 Average LAeq measured for 24 hour, day and night time periods

at each location 181

Table 10.1 Comparisons between measured and MLE-RT20 values 205

Table 10.2 Numbers of triggers recorded during the simulations 206

Table 10.3 SLM 1 with curtains open 207

Table 10.4 SLM 1 with curtains drawn 207

Table 10.5 SLM 2 with curtains open 207

Table 10.6 SLM 2 with curtains drawn 207

Table 10.7 Locations with data available for MLE-RT20 estimation 208

Table 10.8 Day time data shown in 4 hour windows; overall mean estimate

with 95% confidence intervals 209

Table 11.1 Summary of the objective and subjective data collected during the study 217

Table 12.1 World Health Organisation guidelines for hospital wards and treatment rooms 248

Acoustic Design for Inpatient Facilities in Hospitals Acknowledgements

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xv

Acknowledgements

This piece of work has been funded as a ‘Case Award’ by the Engineering and Physical

Sciences Research Council (EPSRC) and by Arup Global Healthcare.

Firstly, I would like to thank the members of the Redevelopment Team at Great Ormond

Street Children’s Hospital, and those members of the Estates Teams at Bedford Hospital and

Addenbrooke’s Hospital who facilitated this research. Without their time and support, this

research would not have been possible. I would also like to thank the study ward managers

for their cooperation, and all the ward staff and patients who have taken time to complete the

study questionnaires.

This work would also have not been possible without the unending support, patience and

kindness of my supervisor Professor Bridget Shield. I would like to thank you for having faith

in me and allowing me finally to fulfil my true potential.

I would also like to express my gratitude to my supervisor Rosemary Glanville for sharing her

extensive knowledge and experience of healthcare buildings, and for providing me with

invaluable guidance and support.

I would like to extend my thanks to Russell Richardson at RBA Acoustics who gave me the

initial opportunity to gain some valuable experience in the field of acoustics, and to Peter

Attwood of Acoustic Associates (Sussex), without whom I would never have embarked on this

journey.

Finally, a thank you to all my friends and family for believing in me and for always ‘being

there’.

Acoustic Design for Inpatient Facilities in Hospitals Glossary and definitions

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xvi

Acoustic glossary and definitions

Sound and noise

‘Sound’ refers to the harmonic pressure variations that we hear in air and is an important part of our everyday world. Too much sound can be annoying, even dangerous. ‘Noise’ usually refers to unwanted sound. General environmental and building noise consists of sound that is composed of many different frequencies.

The decibel and sound pressure

The decibel (dB) is the main measurement unit in acoustics. It can be the measure of the magnitude of sound, changes in sound level and a measure of sound insulation. The decibel is not an absolute unit, but the ratio of two levels expressed in logarithmic form.

• A 1 dB increase in level is un-noticeable in everyday life.

• A 3 dB increase would be barely perceptible (even though it is actually a doubling of sound energy).

• A 10 dB change in level is perceived as the doubling in loudness.

The pressure fluctuations caused by sound waves in air are called sound pressure. The lowest sound pressure level which can be heard is 0 dB, known as the threshold of hearing. The highest level which can be tolerated is called the pain threshold and is around 120 dB.

The response of the human ear and ‘A-Weighting’

The response of the human ear is dependent upon the frequency characteristics of the sound. The ear is not equally sensitive to sound at all frequencies, being less sensitive at low and very high frequencies, with peak response around 2500 to 3000 Hz

The vast majority of noise measurements made are in A-weighted decibels (dBA). The A-weighting is an electronic frequency weighting network which attempts to build the human response to different frequencies into the reading indicated by a sound level meter, so that it will relate to the loudness of the noise. The measured readings are denoted with either an ‘A’ as in 90 dBA or a subscript in the case of LAeq, LA90, and LAmax. The subscript ‘Z’ denotes that the measured sound level is unweighted.

A- Weighted Equivalent Sound Pressure Level (LAeq)

Most measured noise is not steady, but fluctuates significantly in level over a short period of time. It is not easy to find a measure which accurately quantifies what is heard with a single number. The LAeq is the A-weighted equivalent continuous sound pressure level. It is an average of the total amount of sound energy measured over a specified time period (commonly a 1 hour period).

If noise is measured for discrete periods of time, the overall LAeq,T can be calculated using the following equation:

LAeq,T = 10log[(t1.10L1/10

+ t2.10L2/10

+ t3.10L3/10

+ ……. TN.10LN/10

)/T]

Where t1 is the time at noise level L1 dBA

t2 is the time at noise level L2 dBA

t3 is the time at noise level L3 dBA, etc.

….and T is the time over which the value is required.

LAmax, LAmin and Statistical Parameters

The LAmax is the A-weighted maximum sound pressure level during a measurement period.

The LAmin is the A-weighted minimum sound pressure level during a measurement period.

Statistical parameters (sometimes called noise percentile levels) are the sound pressure levels exceeded for a certain percentage of the measurement period.

LA10 and LA90 are the most commonly used, where LA10 is the level exceeded for 10% of the time and LA90 is the level exceeded for 90% of the time.

LA90 is used to represent background noise levels.

Fast and Slow Time Weightings

Time weightings determine how quickly a sound level meter (SLM) responds to changes in the sound pressure level. Most measurements are now made with a fast weighting selected, unless otherwise specified by the relevant standard.

When sampling is set to ‘fast’ the SLM is sampling over a number of 0.125 s periods and all parameters are calculated from these measurements.


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xvii

When sampling is set to ‘slow’ the SLM is sampling over a number of 1 s periods and all parameters are calculated from these measurements.

As the SLM is responding more slowly when set to ‘slow’, impulsive measurements such as LAmax would give lower sound pressure level readings (as a rule of thumb 5dB less could be expected) and LAmin values would be higher than expected. The difference between LAeq measurements would not be so significant (perhaps 1dB depending on the specification of the SLM).

Frequency (Hz)

Frequency is defined as the number of oscillations per second and is measured in Hertz (Hz).

A healthy young person can hear frequencies from 20 Hz to 20,000 Hz (the lower the value the lower the pitch).

Loudness

Loudness is a measure of the subjective impression of sound

Reverberation Time (RT)

The reverberation time is defined as the time it takes for sound to decrease by 60 dB. Long reverberation times usually exist in spaces with hard surfaces and minimal sound absorption (like curtains, carpets and soft furnishings). Sounds within reverberant rooms may seem hard-edged and even echo-y. With high levels of background noise present, the nature of a reverberant room is such that speech intelligibility may be affected, causing voices to be raised.

To determine the length of the reverberation time, different parts of the reverberation curve are used. This is illustrated by the graph below:

To calculate the Early Decay Time (EDT), the time taken for sound to decrease by 10dB is used and multiplied by a factor of six. The EDT is known as the “early reverberation time” and is considered to better reflect how we perceive the reverberance in the room.

The descriptors T20 and T30 are usually called “late reverberation times” as they measure the later parts of the curve.

When calculating T20, the time taken for the sound to decay by 20dB is used and is trebled to give the reverberation time. It should be noted that the evaluation does not start until after the sound level has already fallen by 5dB.

When calculating T30, the time taken for the sound to decay by 30 dB is used and is doubled to give the reverberation time. As with T20 calculations, the evaluation does not start until after the sound level has already fallen by 5 dB.

If the reverberation curve is straight, the EDT, T20, T30, will all produce the same value. However, the reverberation curve is usually not straight (shown by a dashed line on the graph), which means that the descriptors will differ.

The room volume, room shape, and the amount of sound absorbing material present all have an effect on the reverberation time.

Sound Absorption Coefficient

The sound absorbing properties of a material are expressed by the sound absorption coefficient, α, as a function of the

frequency. α ranges from 0 (total reflection) to 1.00 (total absorption).

Time (secs)

So

un

d p

res

su

re l

ev

el

(dB

)


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xviii

Sound Absorption Class

In accordance with international standard EN ISO 11654, the absorption classes are designated A-E, where absorption class A has the highest sound absorption. The graph below illustrates the difference in properties of each class.

Sound absorption table

Frequency (Hz)

1. Absorption class A

2. Absorption class B

3. Absorption class C

4. Absorption class D

5. Absorption class E

6. Unclassified

Reflective building materials have low absorption coefficients (α), for example plastered walls have a value as low as α=0.02. Sound absorbing materials have a relatively high absorption coefficient, for example some ceiling tiles can have value as high as α=0.95 at some frequencies.

Ab

so

rpti

on

co

eff

icie

nt

(α)

Acoustic Design for Inpatient Facilities in Hospitals Abstract

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1

Abstract

There is an increasing body of research into the acoustic environment of hospitals which provides

evidence of the detrimental effects of noise on the well being and comfort of patients and on staff, and

of a significant rise in hospital noise levels in recent years. Much of this evidence has focused on

specific areas of healthcare such as critical care and operating theatres, with comparatively few

studies carried out within general inpatient wards and in UK hospitals.

The current study aims to investigate, through objective and subjective surveys, the noise climate and

acoustic design within general inpatient facilities in the UK, and their influence on the acoustic comfort

of patients and staff. Noise and acoustic surveys have been carried out in six inpatient wards in three

major UK hospitals, with corresponding questionnaire surveys of staff and patients.

Noise measurement data has been analysed to build up a comprehensive understanding of the

contributing factors to noise in both single room and multi-bed patient accommodation, and at the

main ward nurse stations. Comparisons are made between patient accommodation types; medical

and surgical wards; building construction types; ward layouts; and finishes. The potential impact of the

design for infection control on acoustic comfort is also examined.

Patient and staff perceptions of noise are investigated, with the identification of the most annoying

and disturbing noise sources. Attitudes to noise and factors such as age, length of stay, bed location

and length of service are considered where appropriate.

The problem of hospital noise in inpatient wards is found to be very complex in nature, with many

different factors affecting the noise climate. The study concludes that a multi-faceted approach is

required if any significant improvement is to be achieved. This should be centred on three main areas

(i) optimising the acoustic design of the ward, (ii) minimising the disturbance caused by equipment in

use on the ward and (iii) modifying the behaviour of those on the ward. Discussion of these areas is

provided and potential areas of noise control investigated. The observational culture of nursing in UK

hospitals is also considered in relation to ward design.

Two further pieces of work have been carried out in addition to the main study. The first investigates

the effects of changing a non acoustic suspended ceiling for one with good acoustic properties. Noise

levels and reverberation times prior to and after this change are measured and improvements found.

The second piece seeks to validate an estimation method for reverberation times in occupied spaces.

Using noise data captured during the main study, the estimated data is found to demonstrate similar

accuracy to standard measurement techniques, and as such the method could potentially be used to

provide reverberation time estimates in occupied areas where real time measurements are not

practical or possible.

Acoustic Design for Inpatient Facilities in Hospitals Introduction

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2

Introduction

1.1. Background

Concern about noise in healthcare is not a recent phenomenon. In her book Notes on Nursing

(Nightingale, 1860), first published over 150 years ago, Florence Nightingale devoted an entire

chapter to noise and its negative effects. She warns… ‘Unnecessary noise, then, is the most cruel

absence of care which can be inflicted on the sick and well.’

Research into the subject area of hospital noise is surprisingly diverse, with Ulrich et al (2004) citing

no less than 130 studies which focus on the subject. A clear trend of rising hospital noise since the

1960’s has been identified by Busch-Vishniac et al (2005), with average increase in noise levels per

year of 0.38 dB during the day and 0.42 dB at night. This increase in noise levels appears to be

universal in nature, with many international studies showing similar trends.

There is also increasing evidence of the detrimental effects of noise on patient wellbeing and on staff,

with noise induced stress being linked to burnout of critical care nurses (Topf and Dillion, 1988).

Studies have also linked noise levels to patient recovery rates (Fife and Rappaport, 1976) and

associated improvements in acoustic design with reductions in patient re-admission rates (Hagerman

et al, 2005). It should be noted, however, that much of the evidence concerning the impact of noise on

patients and staff is focused on a small number of frequently cited studies.

A review of the literature has found that research into hospital noise has tended to concentrate on

busier areas within hospitals, such as critical care units, intensive care units and operating theatres,

with limited research carried out in inpatient wards. Patients in inpatient wards are generally

recovering from either a severe infection or from surgery, and so require restful conditions that are

beneficial to their recovery. Research on the impact of noise in this area is felt to be of at least equal

importance to research into noise in critical care areas.

1.2. Aims and objectives

The aim of this study is to provide a comprehensive insight into the noise climate in inpatient hospital

wards. The research involves both objective measurements which help build up an understanding of

noise levels and the sources of high level noise; and questionnaire surveys of staff and patients on

the wards, which explore their perceptions of noise. Six inpatient wards in three major hospitals are

the subject of the study, with a mixture of medical and surgical wards and types of building stock.

Hospital buildings of differing ages, construction type, ward design, and finishes are all considered.

The findings of the study will help to inform the decision making process in both new building design

and the refurbishment of existing wards, and to provide general advice around the choice of ward


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3

equipment and technological systems to be commissioned. The findings also enable a critical review

of current standards to be carried out to ascertain their applicability in relation to occupied buildings.

1.3. Overview

This thesis consists of 12 chapters. Chapter 2 discusses relevant guidance and standards for

healthcare buildings and is followed by an extensive literature review in Chapters 3 and 4. The

findings of these three chapters inform the study methodology which is discussed in Chapter 5 and is

trialled during the pilot study detailed in Chapter 6. The main study locations and results of the

subsequent objective and subjective studies are discussed in Chapters 7 and 9, with a further overall

analysis of these provided in Chapter 11. A full discussion of the study findings in relation to noise

control are provided in Chapter 12. Chapters 8 and 10 are concerned with the results of a ceiling

change carried out in one particular ward, and the validation and use of a reverberation time

estimation method for occupied spaces.

In order to understand the role of acoustic guidance documents and standards in healthcare

buildings, a review is carried out in Chapter 2. Specific guidance on the acoustic design of healthcare

buildings was found to exist as early as 1966, and the changes to standards over time are

considered. Comparisons with European standards are made; the World Health Organisation

guidelines are assessed; and specific design criteria in relation to control of infection on hospital

wards is discussed. In relation to this study, which is concerned with occupied buildings, the

relevance of much of the documentation in this chapter is found to be minimal.

Chapters 3 and 4 aim, through critical evaluation, to build up a thorough understanding of previous

research carried out in the field of hospital noise and acoustic design. For the purposes of clarity

these chapters are divided into a number of categories: noise measurement studies; sleep studies;

the effects of behaviour modification on hospital noise; the effects of room acoustic design

modifications on hospital noise; the effects of noise on healthcare staff; and the effects of noise on

patients. Within each category a number of papers are summarised and some critical appraisal is

made of methods used where appropriate. Discussion of the study findings, design limitations and

areas found to be lacking in research is provided.

Conclusions drawn from the literature review in Chapters 3 and 4 were seminal in informing the

design of the study. Chapter 5 outlines the aims and objectives of this study and provides further

detail of the objective and subjective survey methods used. The preliminary work involved in obtaining

ethical approval and the necessary permissions to carry out the study within occupied ward

environments are also discussed.

To trial the study methodology, a pilot study was carried out in a post surgical inpatient ward at Great

Ormond Street Children’s Hospital, London. Chapter 6 discusses the considerations required when

working in a healthcare environment, including the appropriate location of measurement equipment


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4

and the distribution of questionnaires. Detailed results of the objective noise level measurements are

presented and the subjective perceptions of the noise climate of both patients and staff examined.

The main study was undertaken in two inpatient wards at Bedford Hospital and three inpatient wards

at Addenbrooke’s Hospital, Cambridge. The results from these study wards are reported in Chapters

7 and 9 respectively. Details of the objective measurements made in each ward are discussed and

the subjective perceptions of staff and patients are compared. Further analysis of these results are

presented in Chapter 11, which considers factors affecting noise levels, and staff and patient

perceptions.

Two further pieces of work were carried out in addition to the main study. Planned refurbishment

works were due to take place in the medical ward at Bedford Hospital, which had been the subject of

objective and subjective surveys. The works were scheduled to start several weeks after the end of

the study data collection, and this enabled a ceiling intervention study to be carried out in which non

acoustic ceiling tiles were replaced by tiles with good acoustic properties. Noise levels and

reverberation times were investigated prior to and after this change and the results are reported in

Chapter 8.

The second piece of work was the validation of a reverberation time (RT) estimation method. This

method, known as the Maximum Likelihood Method, was developed by the University of Salford for

use with recorded speech or music. Since making RT measurements in occupied hospital wards is

not practical using standard methods, an alternative method to estimate the RTs of occupied wards

was considered to be extremely useful. Validation of this method was carried out using data captured

from the study wards and is discussed in detail in Chapter 10.

Chapter 12 summarises the findings of this study in relation to noise control in inpatient hospital

wards; the applicability of standards to occupied hospital buildings; and the usefulness of particular

acoustic measurement parameters in the reporting of hospital noise. Study conclusions and

recommendations for further work are discussed in the final chapter of this thesis.

Acoustic Design for Inpatient Facilities in Hospitals Acoustic standards and guidance

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5

2. Acoustic standards and guidance

2.1. Introduction

This chapter reviews the history of guidance relating to acoustic design of UK healthcare facilities up

to the present time. The differences between UK and European guidance are explored, and the

relevant section of the World Health Organisation ‘Guidelines for Community Noise’ summarised.

The final section presents further discussion on other aspects affecting acoustic design in

healthcare.

2.2. UK design guidance

In the UK, design of healthcare buildings is governed by guidance published by the Estates and

Facilities Division within the Department of Health. Essentially, the guidance falls into the following

two categories:

� Health Building Notes (HBN) which provide advice to project teams designing and planning

new buildings and refurbishing existing buildings.

� Health Technical Memoranda (HTM) which provide estates and facilities professionals with

guidance on the design, installation and running of specialised building service systems.

It appears that some guidance was available as early as 1966, with information on noise control

provided in the Ministry of Health Hospital Design Note 4: Noise Control (Her Majesty’s Stationery

Office, 1966). As with more recent guidance this design note provided general advice on plant noise,

the performance of internal partitions and external wall construction. More surprisingly, suggestions

for effective noise control in occupied wards were given for a variety of items such as ‘quiet curtain

tracks’; hospital trolleys with good quality rubber tyred wheels; the use of steel sinks coated with

rubber on the underside to minimise noise; and the suggestion that TVs in multi-bed wards should be

wired through patients’ headphones only.

For the purposes of this review, the three most recent guidance documents affecting acoustic design

of healthcare buildings are examined in further detail. These are HTM 2045 Acoustics: Design

Considerations (NHS Estates, 1996), HTM 56 Partitions (NHS Estates, 1997) and HTM 08-01

Acoustics (The Stationary Office, 2008).

HTM 2045 Acoustics: Design Considerations (NHS Estates, 1996) contained partition performance

requirements as well as advice on many other aspects of acoustic design including mechanical

services noise, impact noise, vibration, façade sound insulation, and reverberation times. Not only

did the guidance provide specification of acoustic design criteria, it also provided information on the

sources of noise and provision of noise control, and an eleven page section on the principles of


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6

acoustics. At a total 53 pages in length, it was considered by some as rather impractical (Popplewell,

2008).

HTM 56 Partitions (NHS Estates, 1997) provided general design guidance on the construction and

performance of internal partitions, with some specific performance criteria to ensure adequate

privacy between rooms in a healthcare setting. The partition performance criteria set out in this

guidance document were less stringent than those provided in HTM 2045 as they were specified in

terms of sound reduction, with no implied requirements for flanking control or need to pay attention to

junction detailing.

Confusingly, HTM 2045 was intended to take precedence over HTM 56, although it was published a

year earlier. However, in the construction industry both guidance documents were considered to be

current. Many healthcare buildings were built to the less comprehensive and less stringent criteria

set out in HTM 56, as this was considered to be a less expensive option. To end this confusion HTM

56 was finally revised in 2005. All guidance on acoustic performance was removed and the standard

was re-written to refer to HTM 2045, which was itself superseded in 2008 by HTM 08-01, and is

discussed in the following section.

2.2.1. HTM 08-01

The latest acoustic design guidance ‘HTM 08-01 Acoustics’ was published in 2008 (The Stationary

Office, 2008) and superseded HTM 2045.

Popplewell (2008) explained the drivers for change behind the latest standard and discusses some

of the difficulties associated with the implementation of HTM 2045. A number of examples were

provided by the author to illustrate these difficulties, following his own experiences of working with

several large Private Finance Initiative healthcare projects, and are shown below.

� The reverberation time criterion was felt to be unrealistic in areas where absorptive finishes

were not appropriate for the reasons of infection control, for example in an operating theatre.

� The building services noise criterion was felt to be impractical due to the need for dedicated

air handling systems in specific areas.

� The impact sound performance requirements of HTM 2045 could not be guaranteed by

contractors.

A number of aims of the new standard were suggested by Popplewell (2008), with the emphasis on

creating a simple, practical and effective standard. HTM 08-01 was designed to:

� simplify and shorten the text of HTM 2045

� make sure recommendations were practical and appropriate


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7

� clarify aspects which were considered to be open to misinterpretation in the previous

standard

� remove specific limits where they either imposed unnecessary costs or where they were

unachievable from a practical perspective

� allow for the incorporation of new technologies

As published, the HTM 08-01 is indeed a more streamlined version of the previous standard. It

recommends acoustic criteria for both noise intrusion and mechanical services noise. Footfall, plant

vibration and internal sound insulation requirements are also considered. Examples are shown in

Tables 2.1 & 2.2.

Table 2.1 Example of criteria for intrusive noise from external sources, HTM 08-01

(The Stationary Office, 2008)

Table 2.2 Example of criteria for internal noise from mechanical and electrical services, HTM 08-01


Several matrices are provided to simplify the calculation of the internal sound insulation

requirements. These matrices take into consideration the privacy requirements and the potential

noise generated within each room type. Tables 2.3 and 2.4 provide examples.


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8

Table 2.3 Example of sound insulation parameters of rooms, HTM 08-01


Table 2.4 Example of sound insulation ratings (dB, DnT,w) to be achieved on site, HTM 08-01


One of the main differences between this and the previous standard is the lack of specific guidance

on room acoustic design. HTM 2045 specified reverberation times for rooms of different functions

with volumes less than 1000 m3, as shown in Figure 2.1, where room types A, B and C are

consulting rooms, multi bed wards and bathrooms respectively.


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9

Figure 2.1 Recommended RTs for different room functions and volumes,

HTM 2045 (NHS Estates, 1996)

The latest standard is much more general, providing guidance regarding the amount of acoustic

absorbency used, but does not include precise guidance on room reverberation times, advising that a

‘reverberation-time criterion should be agreed depending on the specific requirements for use of the

space’.

The guidance acknowledges that the use of acoustically absorbent materials ‘can have a dramatic

effect on the acoustic comfort in a room’ and is particularly necessary where speech intelligibility is a

requirement. It states that sound absorbent treatment should be used in all areas, including

corridors, and recognises that there may be issues surrounding the use of sound absorbent

materials where ‘cleaning, Control of Infection, patient safety, clinical and maintenance requirements

allow.’

The guidance suggests that the most appropriate area for acoustically absorbent material should be

a ceiling, with the minimum absorption area equivalent to 80% of the area of the floor when using a

Class C absorber (see Glossary).

Occupied hospital buildings

It is important to note that HTM 08-01 is applicable to a newly built or refurbished unoccupied

healthcare facility, where specific systems can be measured alone. Most of the values specified

however cannot be compared with measurements made in an occupied building, where systems

cannot be isolated. Nevertheless, there is some general guidance which is relevant for occupied

buildings and is listed below:

Medical Equipment

The standard states that ‘ideally it should be chosen so that it does not adversely affect the use of

the surrounding space’ and that ‘quiet equipment should be chosen.’


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10

Nurse-call Systems

Guidance is given regarding the choice of nurse-call systems to the effect that ‘nurse-call systems

can disrupt sleep; therefore non-audible systems should be considered; especially at night.’ Also it is

suggested that ‘audible alarms intended for staff should be located such that they cause minimum

disruption to patients.’

The standard also contains a checklist for the most important acoustic issues. Some internal ‘fit-out

equipment’ and ‘management issues’ listed are relevant when considering noise levels in occupied

wards, and the relevant extract of the checklist is shown in Table 2.5.

Table 2.5 Extract from Chapter 8 ‘Checklists’, HTM 08-01 (The Stationary Office, 2008)

2.3. European healthcare design guidance

Bergmark and Janssen (2008) compiled an overview of international standards focussing on those

portions which dealt with room acoustics within healthcare buildings. Comparison was made

between standards from Sweden, Germany, Finland, Norway, UK, Denmark and The Netherlands.

The UK was found to be the only country with a specific healthcare guidance document. Sweden,

Finland, Norway and Denmark have healthcare specific sections within wider guidelines, whereas

Germany and the Netherlands use general workplace criteria.

The study noted that the UK standard, HTM 08-01, was the only standard which did not provide

specific guidance on either room reverberation times or speech intelligibility. It was also noted that,

with the exception of UK and Denmark, ‘comfort classes’ were mentioned in each of the standards.

These comfort classes aim to define the level of acoustic comfort for the user by using certain

acoustic parameters such as reverberation times and levels of building services noise.

Table 2.6 provides a summary of the seven European standards and guidelines reviewed.


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11

Table 2.6 Standards and guidelines for healthcare design in Europe (Bergman and Janssen, 2008)

Table 2.7 summarises the acoustic parameters specified by the standards for the purposes of

acoustic room comfort.

Table 2.7 Acoustic parameters (Bergman and Janssen, 2008)

2.4. World Health Organisation guidelines

The most recent edition of the World Health Organisation (WHO) Guidelines for Community Noise

was published in 1999 (Berglund et al, 1999). The guidelines seek ‘to consolidate actual scientific

knowledge on the health impacts of community noise and to provide guidance to environmental

health authorities and professionals trying to protect people from the harmful effects of noise in non-

industrial environments’.


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12

In relation to noise in hospitals, the guidelines state that ‘the critical effects of noise are on sleep

disturbance, annoyance and the communication interface, including interference with warning

signals’. Values of LAeq are provided for day time, which is listed as 16 hours from 07.00 – 23.00. LAeq

and LAmax values are provided for night time, which is listed as eight hours from 23.00 – 07.00, with

LAmax values measured on a fast setting. A summary of the guidelines is shown in Table 2.8.

Table 2.8 World Health Organisation guidelines for hospital wards and treatment rooms

Specific Environment Critical Health

Effects LAeq (dB) Time Base (Hours) LAmax (dB)

Hospital, ward rooms,

indoors Sleep disturbance 30 Night time (8 hours) 40

Hospital, ward rooms,

indoors Sleep disturbance 30

Day time and evenings

(16 hours) -

Hospital, treatment rooms,

indoors

Interference with

rest and recovery

As low as

possible

The guidelines also suggest ‘since patients have less ability to cope with stress that the LAeq level

should not exceed 35 dB in most rooms where patients are being treated or observed’.

2.5. Control of Infection

In the UK, Healthcare-Associated Infection (HCAI) has become an increasingly high profile issue

over recent years. The result has been increased pressure on UK hospitals to clean more frequently,

more thoroughly and with stronger cleaning agents. Several guidance documents have been

produced which provide advice on the use of suitable materials to withstand the new cleaning

regimes. These materials include flooring, wall coverings and ceiling finishes, the most relevant to

the current study being the use of acoustic ceiling tiles. The relevant paragraphs of each document

are explored in the sections below.

‘Control of Infection teams’ have been set up in all hospitals to make general decisions in relation to

hospital HCAI policies. These teams interpret the guidance documents in different ways, some more

vigorously than others.

2.5.1. HTM 60

HTM 60 (NHS Estates, 2005) deals with all aspects of suspended ceilings, including fire performance,

ceiling tile composition, wind loading, and details of grid construction. Only two sections are of

relevance in terms of HCAI and these detail the physical characteristics of the ceiling tiles to be

installed, and provide advice on hygiene and cleaning.


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13

The guidance divides room types into six different categories and lists suitable ceiling finishes to be

used for each. For example, Category 1 applies to operating theatres; Category 4 applies to multi-bed

bays or single patient rooms; and Category 5 to storerooms. Table 2.9 shows that within a Category 4

room, all ceiling types may be used, whereas in a Category 1 room only smooth, imperforate, jointless

ceilings are advised.

Table 2.9 Recommended ceiling characteristics for hospital room types, HTM 60

(NHS Estates, 2005)

In the section entitled ‘Hygiene and cleaning’, the guidance discusses a new ‘model cleaning contract’

for hospitals which, it states, has three key aspects:

1. The National Standards of Cleanliness. This document discusses possible measures for

HCAI cleaning and disinfection.

2. NHS Cleaning Manual. This manual sets out best practice methods for cleaning.

3. Cleaning frequencies. These should be determined to address the element of risk identified

within the National Standards of Cleanliness and should take into account any further advice

and guidance in the model cleaning contract and the NHS Cleaning Manual.

At the time of writing, the NHS Cleaning Manual is no longer readily available, even though HTM 60 is

still current and has not been amended to reflect this.

2.5.2. National Standards of Cleanliness for the NHS

There are several relevant sections in the National Standards of Cleanliness for the NHS (NHS

Estates, 2001) which list the cleaning requirements and cleaning frequencies for walls, skirting boards

and ceilings.

The guidance states that ‘internal and external walls and ceilings are to be free of dust, grit, lint, soil,

film and cobwebs’ and that ‘walls and ceilings are free of marks caused by furniture, equipment or

staff’. Further information can be seen in terms of cleaning time scales for walls, skirting boards and

ceilings.

Table 2.10 provides information on cleaning frequencies by area type.


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14

Table 2.10 Cleaning frequencies in terms of area type priority

Priority Frequency Time Frame for Rectifying

Problems

A Constant, cleaning critical Immediate

B

Frequent, cleaning important and requires

maintaining 0-48 Hours

C

Regular, on a less frequent scheduled basis

and as required in between 2-7days

D Infrequent, or on a scheduled or project basis 1-4 weeks

Priority A applies to operating theatres, ICU and similar units and Protective Isolation Areas.

Priority B applies to sterile supply areas, A&E, pharmacy, general wards and daily activity areas,

rehabilitation areas, residential accommodation, pathology, kitchens, outpatients’ clinics, treatment

and procedure rooms, cafeteria and public thoroughfare.

Priority C applies to general pharmacy, laboratories, mortuary, medical imaging, waiting rooms and

administrative areas.

Priority D applies to non-sterile supply areas, record archives, engineering workshops, plant rooms

and external surrounds.

2.5.3. HFN 30 Infection Control in the built environment

HFN 30, Infection Control in the Built Environment – Design and Planning (NHS Estates, 2002) states

that ‘if the burden of healthcare-associated infection is to be reduced, it is imperative that architects,

designers, and builders be partners with healthcare staff and infection control teams when planning

new facilities or renovating older buildings’.

In relation to ceilings, the guidance stresses the importance of high quality finishes and recommends

that ceilings with smooth, hard, impervious surfaces are installed in theatres and isolation rooms. The

guidance warns that during maintenance work, suspended ceilings can allow dust to fall onto the area

below and therefore this type of ceiling should therefore be avoided in isolation rooms, operating

theatres and treatment rooms. There is no mention of ceiling types for general inpatient wards.

2.6. Discussion

The latest UK design guidance has been simplified to be as practical as possible. Popplewell (2008)

mentions that in particular the internal sound insulation matrices have been well received by

contractors who have found them simple to use and understand. Design guidance of this type aims

to go some way to minimising external noise break-in, plant noise, and noise transmission between

rooms and when put into practice appears to be successful in these areas, as shown by Boulter

(2007).


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15

The relevance of the HTM guidance to the current study is fairly limited, as the study is investigating

noise levels in occupied wards. Only guidance regarding the use and choice of a number of internal

systems has some application.

The omission of specific guidance relating to reverberation time values or target values for speech

intelligibility potentially provides designers and contractors with a ‘get out’ option, which is simply to

ignore these criteria completely. This could have a negative impact on noise levels and acoustic

comfort of wards.

Comparison of the UK guidance with six different European design guidelines indicates that it is

considered important by those countries to specify at least one measure of acoustic comfort. This

again suggests that this omission in the latest HTM could be detrimental to the acoustic environment

in UK hospitals.

The noise levels suggested by the World Health Organisation are relevant in terms of occupied

wards. It would, however, seem that the validity of these levels is questionable as all noise studies

referenced (see Chapter 3) have found levels to be above the WHO guidelines in general.

Guidance documents are available which provide advice on the types of ceiling finishes required and

the cleaning frequencies. The documents are open to interpretation and therefore may be interpreted

more or less stringently at different locations. Some inconsistencies do exist, with one major

guidance document referenced, no longer available.

With regards to the type of acoustic materials for use in areas where there are concerns about HCAI,

no clear design guidelines appear to be available. Acoustic ceiling tiles which will withstand

bleaches and high pressure washing are readily available on the market. It is important that not only

are contractors and designers made aware of these products, but also the hospital Control of

Infection teams, who have an increasing influence on the internal finishes used. Without this

knowledge the use of non acoustic ceiling tiles may become more prevalent, having a detrimental

effect on the acoustic comfort of a room.

2.7. Conclusions

It has been shown that the UK guidance is on the whole less stringent than guidance in other

European countries or the WHO guidelines. In the current study objective levels measured are

compared with current guidelines where appropriate. The following two chapters review previous

research on hospital noise and its effects on staff and patients. Many of the studies reviewed show

that current guideline values are exceeded.

Acoustic Design for Inpatient Facilities in Hospitals Previous research on hospital noise

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16

3. Previous research on hospital noise

3.1. Introduction

There has been a significant body of research into various aspects of hospital noise and acoustics in

the past 50 years. This chapter aims, through critical evaluation, to build up a thorough

understanding of previous research carried out in the field of hospital noise and acoustic design. For

the purposes of clarity this review is divided into four categories: noise measurement studies; sleep

studies; the effects of behaviour modification on hospital noise; and the effects of room acoustic

design modifications on hospital noise.

Within each category a number of papers are summarised and some critical appraisal is made of

methods used where appropriate. Discussion of the study findings and design limitations are provided

at the end of each section.

3.2. Noise measurement studies

The hospital environment is an extremely complex one, consisting of many different areas, including

Accident and Emergency (A&E) departments, operating theatres, intensive care units (ICUs) and

general inpatient wards. In each area, different activities are taking place with patients requiring

different levels of care.

Much of the available literature investigating noise levels in hospitals concentrates on specific

measurement locations. It appears that many of these locations were chosen because of the

perception that they were more ‘noisy’. This makes it difficult to build up an overall picture of the noise

climate across all areas of the hospital.

A large review of previous studies dating from 1960 was carried out by Busch-Vishinac et al in 2005.

In order to identify whether a trend in hospital noise exists, the authors compiled data from all

comparable studies post 1960 which listed LAeq noise measurement values. Although it was

acknowledged that there were some discrepancies in the data (for example, no indication of sampling

rates or the period of time averaging), the study yielded some interesting results.

The findings were three-fold:

i. Not one single study showed a hospital which complied with the WHO guidelines for hospital

noise, raising the question of the validity of these particular guidelines.

ii. The study showed less variation in results than was expected. This was surprising given that

the data was gathered from widely differing sources – different types of medical units and

hospitals situated in a number of different countries throughout the world. It led the authors to

conclude that the problem of hospital noise is a universal one.


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17

iii. A clear trend was shown for rising hospital noise since 1960. The data showed an increase of

0.38 dB per year for day time levels and 0.42 dB per year for night time levels, with a rise in

measured LAeq values from 57 dB in 1960 to 72 dB in 2005 during day time hours, and from

42 dB in 1960 to 60 dB in 2005 during night time hours.

Figures 3.1 and 3.2, reproduced from Busch-Vishinac et al (2005), show the A-weighted

equivalent day and night sound pressure levels as a function of year of study publication. The

error bars indicate that data was given as a range spanned by the error bars.

Figure 3.1 LAeq values measured in hospitals during day time hours as a function of the year of

study publication. (Busch-Vishinac et al, 2005)

Figure 3.2 LAeq values measured in hospitals during night time hours as a function of the year of

study publication. (Busch-Vishinac et al, 2005)

The remainder of this section focuses on the more recent relevant studies of hospital noise, which are

summarised in Table 3.1.


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18

In 1996, McLaughlin et al considered noise levels in a cardiac ICU at the Royal Group of Hospitals,

Belfast, and concluded that they were consistently higher than those stipulated in the WHO

guidelines. LAeq values for the measurement period were found to be above 60 dB at all times and

LAmax values greater than 80 dB were measured as early as 5am.

Two studies of noise in hospitals in the US were published in 1999 and 2001. Holmberg and Coon

(1999) examined noise levels within adult and adolescent day rooms in a state psychiatric hospital in

Indiana, and found levels to exceed those measured in other studies of medical, surgical and

intensive care units. Noise levels in A&E departments in four Phoenix hospitals were measured by

Buelow (2001), who concluded that levels were higher than those in which an individual can

comfortably work. The levels were thought to approach or exceed those that can cause feelings of

annoyance.

Tsiou et al (2008), recorded sound levels during surgical procedures carried out in the operating

theatres of nine Greek hospitals. Comparisons between sound levels measured during non-

orthopaedic surgery and orthopaedic surgery were made. This extensive study showed orthopaedic

surgery to be a particularly lengthy, noisy process and recommended that personnel make use of

hearing protection and undergo regular audiometric tests. Sources of noise were identified and their

sound levels noted.

3.2.1. Limitations of noise measurement studies

Measuring noise within a healthcare setting introduces a number of challenges. Patients are in

hospital because they require care; staff are busy and often working beyond their capacity. To take

measurements in a non-intrusive manner without causing annoyance or suspicion is often difficult.

The Hawthorne Effect

One known issue when undertaking a measurement study in an occupied building, is the reaction of

those people in the vicinity of the measurement equipment. If it becomes known that a study is being

undertaken, people may react in a way that might affect the results. This phenomenon was identified

by Henry A. Landsberger in 1955 when analyzing results from a set of experiments carried out from

1924 – 1932 at the Hawthorne Works, and has become known as the ‘Hawthorne Effect’ (cited by

Bailey and Timmons, 2005). Landsberger defined the Hawthorne effect as ‘a short-term improvement

caused by observing worker performance’.

The Hawthorne effect was thought by Bailey and Timmons (2005) to be significant in their study of

noise levels in paediatric ICU in a large UK teaching hospital. It was noted that once

Table 3.1 Measurement data from studies cited in Section 3.2

Author Date Location Measurement

Period Measured Levels

McLaughlin et al 1996 Cardiac ICU, Belfast 24 hr

LAeq > 60 dB, LAmax > 70 dB (for measurement period) , LAmax =100.9 dB

Holmberg and Coon

1999

State psychiatric

hospital, US

36.5 hrs in total at

different times of day

Mean (arithmetic) = 75.7 dBA, LAmax = 92.5 dB ; Sound peaks consistently between 85 and 90 dB

Buelow et al

2001

A&E departments at 4

hospitals in Phoenix, US

16.00 – 20.00

(4 hours)

LAeq = 69.1 dB, 70.1 dB, 71.1dB, 65.0 dB

LAmax = 76.6 dB, 73.4 dB, 73.0 dB, 75.2 dB

Bailey and Timmons

2005

Paediatric ICU in a UK

teaching hospital

24 hr

Loudest voices measured between 68 and 72 dB; General conversation measured between

50 and 65 dB; Equipment alarms measured between 65 and 83 dB

Busch-Vishinac et al 2005 5 locations within the

Johns Hopkins Hospital

3 x 24 hr

measurements at

each location

LAeq : 50 – 60dB (PICU showing the highest noise levels)

Kracht et al 2007

38 operating theatres at

the Johns Hopkins

Hospital, Maryland, US

24 hr

Orthopaedic surgery LAeq = 66 dB

Neurosurgery, urology, cardiology, gastrointestinal surgery LAeq : 62 - 65 dB

Neurosurgery and orthopaedic surgery LAmax >100 dB for over 40% of the time, with peaks >120 dB

Orellana et al 2007

Adult A&E at the Johns

Hopkins Hospital

24 hr Triage Area LAeq : 65 – 73 dB

General A&E LAeq : 61 – 69 dB

Tsiou et al 2008

Operating theatres at 9

Greek hospitals

During 43 different

procedures

Pre-surgical LAeq : 61.1 - 78.2 dB, LA90 : 49.2 - 61.2 dBA, LAmax : 83.6 - 99.4 dB

Surgical LAeq : 57.4 - 70.1 dBA, LA90 : 48.2 - 58.7, LAmax : 84.7 - 100 dB

Post-surgical LAeq : 60.5 - 74.1 dBA, LA90 : 49.7 - 60.7, LAmax : 78.8 - 106 dB

Connection / disconnection of gas supply responsible for loudest sound peak of 106 dB


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20

members of staff became aware of the study, they changed their behaviour accordingly. The

researchers found that the female staff lowered their voices and made an effort to keep noise levels

down; whereas the male staff made deliberate attempts to make noise by shouting at the microphone

and banging equipment (these impulsive noises were ignored in the results).

It has been shown that it is possible to minimise the influence of the Hawthorne effect. For example,

in the study of noise in a cardiac ICU by McLaughlin et al (1996), discussed in the previous section,

the SLM was concealed in a dummy box which had time, temperature and humidity displays. It was

perceived that these displays were sufficient to satisfy the curiosity of the staff regarding this new

piece of equipment placed in their work environment.

Similarly, Kracht et al (2007), who measured operating theatre noise at the Johns Hopkins Hospital in

Baltimore, placed their sound level meter (SLM) so that it did not interfere with the operations. It was

wrapped in a plastic bag to avoid contamination and this may have made the meter less conspicuous.

It was observed that the staff were generally unaware that the meter was present and so did not

attempt to control conversation levels or the playing of music during the operations.

Acoustic inconsistencies and omissions

Partially due to the restrictions that are inherent in working within an occupied ward, it was found that

many of the studies reported measurements in ways that often prevent study comparison. It was also

noted that many of the studies were undertaken by healthcare professionals with little or no knowledge

of acoustics. In a number of studies certain acoustic criteria were not considered, or important key

elements were omitted from the report.

Further details of typical omissions and inconsistencies are given below:

i. Calculation of the time averaged sound pressure level (SPL)

Some of the studies appeared to calculate the average SPL recorded over a period of time

arithmetically, rather than logarithmically. This method of time averaging yields a lower value

and therefore levels may not be comparable with those studies that provide a logarithmically

averaged LAeq,T value.

ii. Equipment Sampling Rates

Many studies do not state the sample rate settings used on the SLM. For some

measurements this setting can make a difference and therefore studies which do not specify

this cannot be used for comparison purposes.


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21

iii. Unspecified, linear or A-weighted measurements

Measurements reported in some studies were either unspecified or listed as linear un-

weighted values. Without frequency band data, conversion of linear to A-weighted values for

comparison with other studies is not possible.

iv. Only minimum and maximum values reported

Some studies did not list either background levels of the noise or time averaged noise levels,

choosing only to list maximum and minimum values. Without time averaged measurements it

is impossible to put maximum and minimum values into context

v. The position of the sound level meter whilst undertaking measurements.

Some studies were concerned with the noise levels experienced by the patient and positioned

the sound level meter by the bed head, while other studies measured the general sound levels

within an area and in some cases positioned the meter by the nurse station. Alternatively

some studies took readings in a number of different areas to build up an overall picture of the

‘noise climate’. On occasions this positioning information was omitted from the paper

completely.

3.2.2. Understanding the overall hospital noise climate

Due to the singular nature of many of the studies, it has been difficult to build up a full picture of noise

within a hospital as a whole. Measurements are provided for specific settings, but have no context in

which they can be compared with other areas in the same hospital.

In their wide-ranging study, Busch-Vishniac et al (2005) took measurements in five different locations

within the Johns Hopkins Hospital in Baltimore, USA. The locations included a paediatric ICU, an adult

medical / surgical ward and a ward for immuno-compromised patients. The locations were in a variety

of buildings of differing ages (the most recent having being built in 1999, the oldest in 1950). To build

up a full picture of the noise climate in each location, measurements were made in patient rooms,

hallways and at nurse stations.

The study found that there was little difference between the sound levels measured in different

locations, although it did cite hallways as the noisiest areas, followed by nurse stations and patient

rooms. The average recorded levels exceeded the levels specified by WHO guidelines by 20 dB and

by at least 15 dB for LAmax. The authors expressed surprise that the newer building (where noise had

been a consideration during the design and construction) was not particularly quieter than the older

buildings.

This study also examined the frequency spectra of the measured sound. Analysis of the component

parts of the noise can provide extremely useful information regarding the sources of noise. The


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22

spectra were found to be similar in shape for each of the locations and the following observations were

made:

� The low frequency noise was almost certainly related to the air handling systems

� Due to the amount of talking observed, the shape of the mid frequency spectrum could easily

be explained.

� The high frequency noise was thought to be predominantly caused by alarms and mobile

medical equipment. The high velocity airflow system was also thought be influential.

To add to this picture of the hospital noise climate, two further studies were conducted at the Johns

Hopkins Hospital:

Kracht et al (2007) measured noise levels in the 38 operating rooms at the Johns Hopkins Hospital.

Noise levels occurring during each type of surgical procedure were captured and frequency spectra

were also analysed. For neurosurgery and orthopaedic surgery, peak levels were found to be above

100 dBA for over 40% of the time. The highest recorded peaks were in excess of 120 dBA. The results

raised two concerns: the potential for hearing loss and the disruption to clear speech communication.

Orellana et al (2007) recorded LAeq measurements within seven different areas of an adult A&E

department. Levels were found to be 5 dB higher than those recorded in other inpatient units within

the hospital, with the triage area of the department found to be the noisiest. The study raised concerns

regarding speech communication without errors, with additional concerns for the medical staff, since

speaking in a raised voice can in itself be tiring.

3.2.3. Identifying noise sources

In addition to building up a picture of the noise climate within a hospital in terms of noise levels, some

studies endeavoured to provide a list of the main sources of noise.

Some earlier studies relied on an individual observer making lists of those sounds which were

perceived to be the loudest. This was of course difficult to later tally with data measurements and

relied on subjective opinion and accuracy of observation. It also introduced the possibility of the

Hawthorne effect as the observer would probably need to inform those around them of their purpose.

However, measuring noise levels during an un-manned study presents a different problem, namely

how to identify the sources of high level noise.

Hodge and Thompson (1990) tackled this problem by making an audio recording of the entire surgical

procedure as well as making measurements with a sound level meter. This allowed sound peaks to be

identified. However, this method introduced more intrusive equipment into a very sensitive area and

also required accurate synchronising of the equipment, potentially leading to later errors. The study


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23

found that during surgery the main sources of high level noise were the sucker and the ventilator, with

the anaesthetic alarms and intercom also contributing.

In their noise surveys of operating theatres, Kracht et al (2007), reported that it was not possible to link

peak sound pressure levels with specific events (for example the use of a bone saw).

3.2.4. Discussion

The review of the literature on hospital noise levels has indicated that the problem of hospital noise

appears to be universal in nature, with a clear trend of rising noise levels both day and night since

1960. Without exception, all noise measurement studies reviewed found that hospital noise levels

exceeded both the World Health Organisation guidelines and the standards set within their own

particular countries. This finding surely makes the validity of the standards questionable.

The majority of studies evaluated have targeted perceived ‘noisier’ areas of hospital care, with a bias

towards patient noise exposure. Few studies concentrate on inpatient ward noise levels and fail to give

adequate consideration to the working environment for staff.

Some consideration should be given to the potential impact of the Hawthorne effect within the design

of a future study. However, this raises the issue of the ethics of studies undertaken in secret.

Previous studies have failed to build up a robust picture of the noise climate within an entire hospital

ward, with most using only a single microphone position. Measurement intervals also tend to be short

(24 hours or less), with no representative interval established. Identification of noise sources was often

found to be unscientific, with acoustic inconsistencies and omissions in reported data making

meaningful study comparisons difficult.

The new generation of sound level meter may overcome the problem of identification of noise sources

without observers. Due to the large data storage capacity now available, these meters are able to

record a short digital audio file whenever sound levels exceed a certain threshold. The audio files are

automatically synchronised with measured sound levels, and so on playback it is possible to identify

the source and level of a particular sound.

3.3. Sleep studies

Sleep is widely thought to be necessary for the restorative and energy conservation processes (Adam

and Oswald, 1983; Berger and Phillips, 1995), and sleep disturbances have been shown to

exacerbate the pain felt by hospital patients (Raymond, 2001). Many reviewed studies considered the

effects of environmental and medical factors on sleep, but few looked directly at the relationship

between noise and sleep in a hospital environment. This section reviews four studies that were felt to

be relevant to the current study.


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24

Aaron et al (1996) conducted a study to test the hypothesis that nocturnal (midnight to 6am) sound

peaks would be associated with an increase of EEG arousals from sleep in patients in the respiratory

ICU at the Rhode Island Hospital, Providence, USA. A significant difference was found between the

number of sleep arousals in quiet periods and the number in very loud periods. However, due to the

small sample size of six patients and the differing health factors (which prevented realistic

comparison), the study found only an indirect link between sleep disturbance and environmental noise.

Freedman et al (2001) studied 22 critically ill patients with continuous polysomnography (PSG) to

characterize the sleep-wake patterns and objectively determined the effect of environmental noise on

sleep disruption. This study was deemed to be unique at the time as the measurement output from the

sound level meter was relayed to the PSG so that the results could be simultaneously evaluated.

Findings showed that environmental noise was responsible for 11.5% of overall arousals and 17% of

awakenings, but concluded that noise was not responsible for the majority of sleep fragmentation and

therefore may not be as disruptive as previously thought.

Gabor et al (2003) monitored critically ill patients in an ICU and compared the results with a sample of

healthy, unattended individuals who volunteered to take part in the study in ICU to see the effect of

noise on their sleep quality. The study also investigated the effectiveness of a noise-reduction strategy

by monitoring subjects in a single bed room. All subjects were monitored with continuous and attended

PSG.

This study made some interesting findings:

� Fewer than 30% of arousals and awakenings in the ICU patient group were identifiably due to

noise and patient care activities. This suggested that other elements of a critically ill patient’s

environment should be investigated as causes of sleep disruption, and as with Freedman et al

(2001), this is in contradiction to traditional hypotheses.

� The healthy individuals in the sample slept relatively well in the ICU. Noise was responsible for

the majority of their sleep disruptions, although this was unsurprising, as other potential

interruptions such as patient care activities and respiratory ventilation were not

present.

� A quantitative improvement of sleep in single bed rooms was found, but sleep architecture

was nearly identical.

As with the majority of sleep studies, this study was limited by its small sample sizes.

3.3.1. Modification of room acoustics and its effects on sleep

Berg (2001) monitored the sleep patterns of subjects exposed to different sounds in an acoustically

altered hospital room. PSG monitoring was carried out on twelve healthy subjects between 20 and 25

years old with no prior history of sleeping difficulties. The room was a refurbished former three bed

surgical ward in a Swedish hospital with a suspended ceiling. The ceiling comprised sound reflecting


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25

tiles during the first two nights of the study. On the third night the tiles were replaced with visually

identical sound absorbing tiles. There were minor differences measured in the SPL before and after

the intervention. The reverberation time was found to decrease by an average of 0.12 seconds (200 to

5000 Hz).

Twelve different sounds of varying frequencies were played at different levels (27 to 58 dBA). The

study found no significant difference in sound induced sleep stage changes, but did find fewer EEG

sleep arousals in the less reverberant room.

This study did not however deal directly with hospital noise. The type of environmental sounds did not

reflect those that patients would be exposed to in a healthcare setting, and the level at which they

were played was not necessarily representative of that found in a hospital. However, the study showed

that the room acoustic design modification appeared to have some effect on sleep quality and as such

is considered to be relevant.

3.3.2. Discussion

Study findings suggest that, contrary to traditional hypotheses, noise is not responsible for the majority

of sleep disturbances of critically ill patients; however with such small sample sizes, no definitive

conclusion is possible.

The large numbers of uncontrollable factors make it extremely difficult to obtain realistic and

comparable data within this category of studies; especially when studying patient groups. Each patient

is unique, with a different physicality, different health issues, and taking differing amounts and types of

medication. Even when considering two healthy individuals, they would sleep differently in the same

environment, and so, with the introduction of so many additional variables, it is very hard to draw

meaningful conclusions.

3.4. The effects of behaviour modification on hospital noise

Human behaviour has been identified as being responsible for a surprisingly large percentage of high

level noise within hospital settings. It appears that through simple methods, at minimal cost, noise

levels can be lowered by making individuals aware of the direct and indirect impact of their actions.

Elander and Hellstom (1995) measured noise levels for routine activities within a neonatal ICU of a

Swedish University hospital. It was found that many of the high levels were attributable to human

behaviour, for example staff laughter, conversation and careless closing of doors, incubators and

drawers.


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26

As part of the study an education programme was presented to the ICU staff which consisted of three

parts:

� A videotape showing a child's post-operative period (filmed from the child's view-point;

highlighting the child’s reaction to various sounds) - one nurse was surprised to find an infant

wake and start to cry at the sound of her voice.

� Sound level values for various activities were provided to help nursing staff to put the levels

into context.

� Detailed discussions with staff were carried out to identify realistic ways of modifying

behaviour.

Using a dosimeter, noise levels measurements were made in an infant’s cot both before and after the

education programme. The study found an average decrease of 8 dB LAeq following the programme.

Kahn et al (1999) conducted a two part study which sought to limit noise in the ICU of a Rhode Island

hospital by behaviour modification. Firstly, twelve of the loudest sources of noise were identified. It

was found that half of these sources were attributable to human behaviour and thus could be

potentially modified (with talking and the television as the most prominent). A staff training programme

was devised and implemented, following which a behaviour modification programme was enforced for

a three week period. The study found that the programme was effective in reducing the noise levels

and recommended that it be used as one part of a larger noise control programme.

A study conducted by Johnson and Thornhill (2006) came to the same conclusions as Kahn et al, but

stressed the need for support from management in any attempt at long term behaviour modification. A

team effort in noise reduction was required for success.

3.4.1. Discussion

Studies have shown that as part of a training programme staff initially make efforts to modify their

behaviour, especially if the training period is being monitored. However, after this initial period it is

potentially difficult to motivate staff to continue.

Staff must be enthusiastic for behavioural modification programmes to work. These programmes need

frequent re-evaluation, education and feedback to reinforce behavioural change. This is only possible

with 100% support throughout the entire staff hierarchy. Management must realise the benefits of

noise reduction, otherwise this is not a realistic proposition.

For a culture of quiet to be re-adopted within hospitals, a complete change of attitude is required. This

is not only necessary from a staff and management perspective, but also required of visitors who need

to be aware and respectful of the needs of the other patients around them.


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3.5. The effects of room acoustic design modifications

Good room acoustic design essentially means that the acoustics are adapted to the activities being

carried out in the space. In theory, hospital room acoustics should not only aim to reduce the sound

level, but give priority to both speech clarity (as clear communication between staff, and staff and

patients is paramount), and speech privacy for patients.

Hospitals rooms are generally made up of hard, easy to clean surfaces. Carpets and curtains are

rarely used. As mentioned in Section 2.2.1 a suspended ceiling is generally the only feasible area that

can be used for the placement of sound absorbing materials. Ceilings provide a relatively large area

for sound absorbency and this can have the following effects: (i) reduction in the room reverberation

time; (ii) reduction in the measured sound level of the room; (iii) improvement in speech intelligibility.

This section reviews studies where physical changes have been made to room acoustics and the

subjective and physiological impact of patients examined.

3.5.1. Control of Infection and room acoustics

As discussed in Section 2.5, there has recently been a great deal of concern regarding the use of

acoustically absorbent materials in areas where Control of Infection is important. The study described

below by McLeod et al (2007), demonstrates one method of introducing effective, long term noise

reduction, whilst meeting healthcare standards and minimising costs.

The study was carried out in an immuno-suppressed Haematological Cancer ward of the Johns

Hopkins Hospital, Baltimore, US, which had been built with a reflective, solid ceiling after concerns that

the small holes typically found in an acoustic ceiling might harbour bacteria. The chosen approach was

to add custom-made sound absorbing panels to the walls of the unit. These were made by the

research team and consisted of glass fibre wrapped in anti-bacterial fabric, as at the time only a single

vendor was found to be selling suitable material; a review of manufacturers’ literature shows that this

has since improved. Objective and subjective data were collected before and after the installation of

the sound absorbers. It was found that there was an approximate drop of 5 dB in the measured LAeq

and the reverberation time was more than halved. The subjective view was that the unit had changed

from one perceived to be 'very noisy' to one that was 'relatively quiet'

Based on anecdotal evidence, it was concluded that the immediate impact of the sound absorbing

panels was to permit patients, staff, and visitors to lower the level of their voices whilst still being well

understood. It was felt that this probably accounted for the majority of the sound level drop. Staff

commented on how loud the telephone and overhead paging system sounded after installation of the

panels, and subsequent steps were then taken to lower the volume of these systems. The drop in

sound level was also felt to promote a safer environment with greater confidence in understanding

speech.


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3.5.2. Physiological response to acoustic modification

The physiological response of neonatal babies was examined by Johnson (2001). Previous studies

had found higher sound levels inside an incubator than in the open neonatal intensive care unit. It was

thought the primary causes were the incubator operating motor and care giving equipment, such as

the ventilator and suction tubing. Acoustic foam was added to an incubator and found to significantly

reduce environmental noise. The response of the neonatal babies to this noise reduction was

measured as changes in oxygen saturation. It was found that there was a significant correlation

between environmental noise and levels of oxygen support therapy required by the neonates.

A study by Hagerman et al (2005), examined the role of room acoustics on patients with coronary

artery disease admitted to the Huddinge University Hospital, Sweden. The study focussed on changes

of physiological parameters which were previously shown to be sensitive to physiological arousal.

These parameters were heart rate, heart rate variability, blood pressure (systolic and diastolic), and

pulse amplitude. A subjective response from patients was also analysed; this took the form of a

questionnaire with a number of questions about the quality of care.

The study took place over a period of eight weeks. During the first four weeks the ceiling tiles in the

patient rooms and the main work area consisted of sound reflecting plaster tiles (‘bad’ acoustics). For

the last four weeks these ceiling tiles were changed to Class A sound absorbing tiles (‘good’

acoustics). The tiles were visually identical. A total of 94 patients were analysed during the eight week

study period. It should be noted that the average stay within the unit was 17 hours, so no patients

were present during both ‘bad’ and ‘good’ acoustic periods.

Impacts of the changes were:

� During the 'good’ acoustics period sound pressure levels fell marginally, but the reverberation

times were halved. Speech intelligibility (as measured by the RASTI method and by subjective

reports from staff) was found to improve considerably.

� There was found to be a significant difference in pulse amplitude at night between groups

during the ‘bad’ and ‘good’ acoustics periods, together with a significantly greater need for

extra intravenous beta-blockers for patients (suggested to be an indication of pain) with ‘bad’

acoustics.

� Patients treated during the ‘good’ acoustics period considered staff attitude to be much better

than those treated during the ‘bad’ acoustics period.

� There was a higher incidence of re-hospitalisation at both 1 and 3 months in the group with

‘bad’ acoustics compared to the ‘good’ acoustics group. Early mortality was not found to differ.


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3.5.3. Discussion

The study carried out by McLeod et al (2007), showed an innovative way of making sound absorbers

which met Control of Infection standards. As discussed earlier in Chapter 2, it seems that no clear

design guidelines are readily available regarding the choice of acoustic materials for use in areas

where there are concerns about infection control. The review by the authors suggests that this is not

just an issue in the UK, although the study indicated that improvements are being made regarding the

choice of products available, and this had been found to be the case from a recent review of

manufacturers’ literature.

The improvement in the acoustic design of a space (by the addition of sound absorbing materials) has

been shown to improve both objective measurements and subjective perceptions. Speech intelligibility

is also enhanced, resulting in the lowering of voices and hence a quieter noise climate.

Only a single study was found which attempted to link the change of acoustic design with a lowering of

re-hospitalization rates. It is felt that with a sample set of patients suffering from complex and serious

conditions, there are too many variables involved to draw any meaningful conclusions in this regard.

There appear to be few studies which systematically vary acoustic conditions. This is an area which

could usefully be investigated further, however in practice this would be difficult to achieve in a working

hospital environment.

3.6. Conclusions

This chapter has reviewed studies which have objectively measured sound levels in hospitals, and

examined the effects of changing the room acoustics on both noise levels and on the physiological

responses of patients and staff. Many of the results and the limitations of the previous studies have

been used to inform the design of the current study, which is discussed in Chapter 5. The following

chapter discusses previous research which has investigated the effects of noise on staff and patients.

Acoustic Design for Inpatient Facilities in Hospitals The effects of noise on staff and patients

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4. The effects of noise on staff and patients

4.1. Introduction

This chapter focuses on previous research which looked at the effects of noise on staff and patients in

healthcare environments. For the purposes of clarity this review is divided into two categories: (i) the

effects of noise on healthcare staff and (ii) the effects of noise on patients. Discussion regarding study

findings, design limitations and areas which appear to be lacking in research is provided at the end of

each section. It should be noted that in some areas very few studies have been undertaken and these

few are regularly cited in the research literature. This is especially true of studies investigating the

effects of noise on patients.

4.2. Effects of noise on staff

4.2.1. Stress levels and burnout

Topf and Dillon (1988) investigated whether noise-induced stress was a predictor of burnout in critical

care nurses. Two university hospitals on the west coast of America were involved in the study, with

100 critical care staff from a range of backgrounds surveyed. The surveys were designed to build up a

picture of the stress that the healthcare staff felt they were under, and were not only related to noise,

but assessed other factors including stress caused by life events and occupational stress.

The results supported the hypothesis that a greater degree of noise would be linked with a greater

degree of burnout. The study also found that nurses with an intrinsic sensitivity to noise were no more

at risk from burnout linked with noise induced stress than those intrinsically less sensitive.

As part of the study staff were asked to indicate which noises were felt to be the most disturbing.

These were compared to those found in a previous study by the authors examining patients after

surgery. Staff cited beeping monitors, equipment alarms and telephones as the most disturbing

sources; patients cited loud talking in the corridor at night and other patients coughing and snoring.

The study raised the interesting point that the noises most disturbing to nurses may be perceived by

patients as necessary for recovery.

4.2.2. Cognitive function / memory

The studies in the following paragraphs attempt to show the effects of hospital noise on cognitive

function and short-term memory of staff, by simulating surgical environments. The findings are

contradictory; hence it is thought that a simulation of this type of environment in a laboratory is not

wholly representative of a hospital situation.

Murthy et al (1995) examined the effects of noise on cognitive function and short-term memory of a

group of twenty anaesthetists. Following a measurement period within an operating theatre, a 90

minute audio cassette was created to be representative of typical operating room noise. This was


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played to the anaesthetists who undertook a series of tests. The study concluded that exposure to the

recorded noise caused deterioration in mental efficiency and short-term memory in the subjects of the

study.

Moothy et al (2005) evaluated the effect of noise on the performance of a complex laparoscopic task.

Twelve surgeons undertook this task under three controlled laboratory conditions – quiet, noise at 80

to 85 dB and background music. A validated motion analysis system was used to assess

performance. The noise used was monotonous repetition of background operating theatre noise and

did not involve any sudden bursts of sound. It was found that neither the noise nor the music had any

significant effects on task performance. It was considered likely that surgeons had learnt to effectively

block out the presence of the auditory stimuli.

4.2.3. Effects of acoustic design on the work environment

The study by Hagerman et al (2005) cited in Section 3.5.2, not only examined the influence of

different acoustic conditions on patient physiology, but also on the work environment and the staff in a

Coronary Critical Care Unit. During the first four weeks the ceiling tiles in the patient rooms and the

main staff work area were sound reflecting plaster tiles (‘bad’ acoustics). For the last four weeks these

ceiling tiles were changed to Class A sound absorbing tiles (‘good’ acoustics). The tiles were visually

identical.

Thirty six regular members of staff were asked to participate in the investigation of the psychosocial

environment and emotional states, and were required to complete a questionnaire at the start and end

of each shift. The questionnaires were designed in line with the 'demand-control-support model',

frequently used in healthcare to analyse work related stress.

During the ‘good’ acoustics period it was found that staff (particularly on the afternoon shift)

experienced significantly lower work demands and reported less pressure and strain. Staff also

reported feeling more relaxed and less irritable, and considered speech intelligibility to have improved.

Caution must be taken in interpreting results of studies of this nature. Although objective

measurements showed a change in some acoustic parameters, there are many other contributing

factors such as work load and tiredness, which may have an effect on the staff mood and their

perceived stress levels. This study did not appear to take these other factors into consideration, and

as such the findings may be compromised.

4.2.4. Discussion

There appear to be very few studies which deal with the effects of the acoustic design on staff

outcomes such as job stress, work demands, fatigue, and quality of patient care.

Although it appears that each member of staff is individual in their tolerance to and their perception of

noise, one regularly cited area of disturbance is that of equipment noise.


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Interestingly, one study indicates that the noises most disturbing to nurses may be perceived by

patients as necessary for recovery.

Concerns are raised regarding staff speech communication without errors and the fatiguing effects of

having to communicate with a raised voice.

Some evidence exists that staff may be able to effectively tune out auditory stimuli whilst performing

tasks which require a high degree of concentration. However, laboratory studies examining the effects

of noise on surgical task performance proved to be contradictory.

4.3. Effects of noise on patients

4.3.1. Recovery rates

In an opportunistic study, Fife and Rappaport (1976) took advantage of construction work being

carried out outside the University of Minnesota hospital to examine the effects that this might have on

the recovery rates of patients. The building works were situated outside the rooms of patients

recovering from a cataract operation. Comparisons were made between discharge rates a year prior

to the study and discharge rates one year later. It was assumed that discharge dates were

determined by wound healing.

The study sample chosen were patients that were undergoing simple cataract surgery, who were free

of any diagnoses that were likely to cause complications. This made the results of the study less

subject to variation. It was found that the difference between the average length of stay during the

noisy period and the pooled quiet periods was statistically significant, increasing from 8.7 days to 9.9

days (p<0.05, one tail test).

4.3.2. Subjective response to noise

Allaouchiche (2002) undertook a multi-disciplinary study looking at the effects of noise on patients

recovering from the effects of anaesthesia. The study, carried out in the post anaesthesia care unit in

a hospital in Lyon, France, involved 26 adult patients. Objective measurements were taken with the

sound level meter positioned close to the patient’s head. Patients were interviewed two hours after

discharge and asked to complete two questionnaires to assess their experiences on the unit. The first

questionnaire was unstructured; the second was structured and asked questions about common

complaints, including noise.

The study concluded that high levels of noise were present and that the majority of this noise could

have been prevented. However, noise was not perceived by patients as the main cause of discomfort,

with only 19% (five patients) identifying noise as an important factor. Of these, four complained about

conversation and one about equipment alarms. It was shown that approximately 55% of sound peaks

greater than 65 dBA were caused by conversation.


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Pugh et al (2007) note an interesting point in their review of noise studies in ICUs. Each patient is

individual in their tolerance for, and how they view, noise. Some patients like the reassurance of

hearing alarms and having people talking around them because it makes them feel safe. The review

concluded that the impact of noise should be reduced by a three way approach - modifying staff

behaviour and practices, minimising the disruption caused by equipment and alarms and optimising

the acoustic design of the ICU.

4.3.3. Speech privacy

Barlas et al (2001) examined whether patients perceived less privacy in A&E curtained treatment

areas than in walled rooms and concluded that patients from curtained areas did report significantly

less auditory, visual and overall privacy than those in rooms.

The study made several points worthy of note:

� 85% of patients reported a high degree of respect for privacy from the staff.

� A small percentage of patients in the curtained areas withheld portions of their medical history

or refused part of their medical examination because of privacy concerns.

� Older patients believed that they could hear others' conversations with a physician or nurse

more often than younger patients.

� It was felt that due to the sensitive nature of some of the questions posed, responses may not

represent the true feelings of the individuals.

4.3.4. Single bed patient rooms

Van de Glind et al (2007) noted that an increasing number of hospitals have taken the decision to

provide single bed patient rooms. It is not clear if these policy decisions are based on scientific

evidence. The study reviewed the literature currently available on the benefits of single bed rooms,

and examined the following: privacy and dignity, patient satisfaction with care, noise and quality of

sleep, hospital infection rates, recovery rates and patient safety issues. The study concludes that due

to the lack of research, there is currently not enough evidence to prove that the introduction of single

bed rooms is beneficial.

4.3.5. Discussion

Only one single, opportunistic study was found which attempted to link patient recovery rates to noise

levels. Further research in the area would be beneficial, but the number of variables involved in

carrying out studies in healthcare makes meaningful results difficult to obtain.

Although it appears that each patient is individual in their tolerance for and how they view noise, one

regularly cited cause of patient disturbance is staff conversation. It was found that some patients like


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the reassurance of hearing alarms and having people talking around them because it makes them

feel safe.

Privacy concerns may cause patients to withhold portions of their medical history or refuse part of

their medical examination. This appears to be particularly relevant in the case of more elderly

patients.

4.4. Conclusions

This chapter has highlighted the lack of extensive research studies examining the effects of noise on

staff and patients, and the difficulty of obtaining reliable and meaningful data in both hospital

environment and simulated laboratory studies. This lack of data has influenced the current study

which aims to further investigate the subjective perceptions of staff and patients to noise in a range of

ward types. This is discussed further in the following chapter.

Acoustic Design for Inpatient Facilities in Hospitals Study Design

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5. Study design

5.1. Introduction

The aims and objectives of the current study were informed by the literature review, with input from

the industrial partner, Arup Global Healthcare. This chapter outlines the aims and objectives of the

research and discusses the objective and subjective survey methods used in more detail. The

preliminary work involved in obtaining ethical approval and the necessary permissions to carry out the

study within an occupied ward environment of a hospital are also discussed.

5.2. Study outline – aims and objectives

The following conclusions drawn from the literature review were seminal in informing the proposed

study design:

� Very few studies have been carried out in general inpatient hospital wards.

� The majority of previous studies have been undertaken by healthcare staff with little

knowledge of acoustics. This has led to inconsistencies in the use of acoustic parameters;

short or incomplete measurement periods; unknown microphone positioning and a general

lack of rigour.

� Few studies have compared noise levels in multi-bed and single bed patient accommodation;

nor have they attempted to build up an overall picture of the noise climate of a ward.

� There is a noticeable lack of studies carried out in UK hospitals.

� Only one study was found which investigated the relationship between acoustic design and

design for infection control purposes.

� Further studies exploring patients’ perceptions of privacy would be beneficial.

� The current UK acoustic design guidelines are effective in terms of general construction

advice, but have less relevance in terms of occupied ward areas.

The current study therefore aimed to address many of these issues, and this is discussed in the

following sections.

It was decided that the proposed research would be both objective and subjective in its nature. The

objective study would consist of an acoustic survey to obtain data on the noise levels and acoustic

conditions in inpatient hospital wards. The subjective component would aim to build up an

understanding of staff and patient perceptions of noise in the same ward environments by use of

questionnaire surveys.

It was felt that the hospitals involved in the study should be chosen to reflect a broad range of building

and ward designs, different types of inpatient care and a mixture of surgical and medical wards. This


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would allow many useful comparisons to be made. Buildings undergoing refurbishment were of

special interest for pre and post intervention studies.

Individuals working in healthcare estates with links to the Medical Architecture Research Unit at

London South Bank University were contacted to locate possible study sites. Three potential sites

were identified: Great Ormond Street Children’s Hospital, London; Bedford Hospital, Bedford; and

Addenbrooke’s Hospital, Cambridge.

5.2.1. Acoustic survey

The main aim of the acoustic survey was to build up a picture of the noise climate within general

inpatient care wards by making a comprehensive series of noise measurements. The data captured

would include average, maximum and background noise levels and the identification of the sources of

high level noise. Noise levels during the day and night would be investigated to allow for comparison

with relevant standards.

Particular consideration would be given to building construction, ward layout, the amount of acoustic

absorbency provided and how the design for control of infection affected the acoustic comfort within

the space. Where possible, factors such as ceiling finishes, ventilation systems and glazing were also

to be investigated:

It was thought that the use of technology on the ward might have a negative impact on the noise

climate. Staff systems, medical equipment and patient entertainment (including TV and radio) were

therefore investigated to build up an understanding of the effects of their use on the noise climate.

In addition to noise measurements other room acoustic parameters such as reverberation times were

considered to provide further indication of the acoustic comfort of the space.

It was felt that the data captured during these objective studies would be invaluable in understanding

the key elements of the noise climate in inpatient care and link directly into the following areas:

� understanding of the physical and behavioural factors that significantly affect the noise

climate

� the effects of acoustic design changes on the acoustic comfort of a space

� exploration of the conflicts between design for infection control and acoustic comfort

5.2.2. Questionnaire surveys

Initially it was hoped that a subjective assessment of the noise climate in inpatient care could be

undertaken using a semi-structured interview approach, talking to both staff and patients. However it

became apparent that to obtain ethical approval within the project time constraints, a questionnaire

survey approach would be more suitable. Further details concerning the need for ethical approval can

be found in Section 5.5.


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Two questionnaires were designed, one for the ward medical staff and another for patients whose

stay on the ward was longer than 24 hours. The aim of the questionnaires was to build up an

understanding of the perceptions of both staff and patients regarding noise in their environment, and

ultimately to establish whether any relationships existed between the objective data collected on the

wards and the perceptions of the ward users.

Good questionnaire design is paramount if meaningful data is to be collected in a survey of this type.

The use of leading words or questions should always be avoided. As such, a great deal of thought

was given to the type of information that was required, and many questions were discarded before

reaching the final versions.

The length of time taken to complete the questionnaire was also considered. Staff are very busy and

unlikely to complete a survey which may take longer than five minutes. Patients, also, would find a

long questionnaire daunting, especially if they were feeling unwell or weak. With this in mind the

questionnaire was kept relatively short and the layout was designed for clarity and ease of

completion.

Questionnaires in their final form were trialled throughout the pilot study (see Chapter 6). Responses

were reviewed and any questions that were felt to be ambiguous were rewritten.

Further details on the design of the questionnaire surveys can be found in section 5.4 of this chapter,

and sample questionnaires can be viewed in Appendix A.

5.2.3. Comparison studies

The ultimate aim of the study was to make use of the objective and subjective data captured in the

following ways:

� comparison studies of single and multi-bed inpatient accommodation

� comparison studies of inpatient wards situated in buildings of differing age, construction and

layout

� a comparison study of a surgical and medical inpatient ward

� examination of the perceptions of the acoustic environment of patients and staff

� identification of the dominant; most annoying; and most disturbing noise sources

� analysis of noise, acoustic and subjective data in order to suggest methods of noise control,

particularly in the areas of equipment and human interface


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5.3. Acoustic survey methodology

5.3.1. Equipment

The following equipment was used throughout the study:

� Norsonic 140 Class 1 Sound Level Meter

� Norsonic Sound Calibrator Type 1251 (114 dB @ 1000Hz)

� Norsonic Environmental Case with two additional heavy duty batteries

� Additional heavy duty batteries to allow for quick equipment rotation

� 5 m microphone extension cable

� Mini microphone tripod / 300 mm ceiling bracket

To allow for longer term measurements to be made, the sound level meter (SLM) was placed in an

environmental case with two heavy duty batteries. The life of the batteries was such that one week’s

worth of data could be collected at each measurement position before replacements were required. A

five metre extension cable allowed the microphone to be placed away from the environmental case,

which afforded flexibility regarding its positioning, see Figure 5.1.

Figure 5.1 Sound level meter, environmental case and associated equipment

5.3.2. Control of Infection

Due consideration was given regarding the choice of equipment and whether it could be easily wiped

clean if necessary. It was felt that the environmental case, which was made of tough plastic, was

easily cleanable. However the microphone, being extremely sensitive, would not be cleanable to any

degree. It was therefore decided that if the microphone was positioned out of reach, it was unlikely to

be touched and contaminated, and thus unlikely to need specific cleaning for purposes of infection

control. Meetings with a member of the hospital Control of Infection team were held at each study site


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to ensure that the use of the noise measurement equipment was acceptable and met with hospital

infection control policies.

5.3.3. Acoustic parameters

To allow an acoustically robust picture of the noise climate to be built up, the following parameters

were measured: LAeq,1hr, LAmax, LA90, LAmin and LZ(SPL) and reported where appropriate.. The third octave

frequency band spectrum of the sound was also included. Throughout the study the SLM was set on

a fast time weighting.

At each change of measurement location the data captured was downloaded onto a laptop computer

and reviewed further using the software provided by Norsonic, the manufacturer of the SLM. This

software, ‘NorReview’, allowed all captured data to be viewed graphically; to be analysed in detail;

and subsequently exported into a Microsoft Excel spreadsheet for reporting purposes.

5.3.4. Presentation of sound levels

To build up an understanding of the noise climate in each ward location, sound levels are presented

throughout the study in a number of different ways:

The measured LAeq,24hr, LAeq,16hr and LAeq,8hr quoted in tables for each ward are arithmetic averages of

each metric over the number of days in the measurement interval. For example, if five days worth of

data have been collected, the reported LAeq,16hr is the arithmetic average of the five daily measured

LAeq,16hrs.

Where average LAeq,1hr and LA90,1hr levels are shown graphically over 24 hours, this is again the

arithmetic average of each metric over the measurement period. For example, for a five day

measurement period, for the time interval 11.00 to 12.00, the LAeq,1hr would be the arithmetic average

of five LAeq,1hrs measured from 11.00 to 12.00.

Any other sound level presented is defined and labelled.

5.3.5. Measurement interval

Many of the measurement intervals in the reviewed studies were either short (less than 24 hour) or

incomplete. It was felt that to build up an accurate picture of noise in inpatient care it was extremely

important to establish a representative measurement interval. This interval could then be used

throughout the main study. This is discussed further in Section 6.14.

5.3.6. Measurement locations

To fully understand the noise climate of a ward, measurements were undertaken in each type of

patient accommodation and at the nurse stations. For example, if a ward consisted of four bed and

single room accommodation, it was decided that at least two single rooms and two 4-bed bays should


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be measured. This would ensure that the data captured was typical of the accommodation type and

enable comparisons to be made.

5.3.7. Identifying sources of high level noise without an observer

Previous studies conducted in healthcare environments often made use of a team of observers to

note down the sources of high level noise. Identifying these sources is important, as it allows some

noise control or other remedial measures to be put in place to counteract unnecessary noise. Of

course the use of observers is only possible in the short-term. Where longer measurement periods

are proposed, this is not realistic or practical.

The SLM used in the study incorporated built in ‘level above’ trigger functionality. By enabling this

feature, a short sound file is created as soon as the value of LAmax exceeds a specified threshold.

Once the data is downloaded for analysis, each sound file can be reviewed and the sources of the

high level noise identified.

5.3.8. Reverberation times

Reverberation time (RT) is generally used as an indicator of the acoustic comfort of a space and is an

important measurement in the field of room acoustics. There are a number of methods used to

measure the RT value. The two widely used methods listed in the British Standard BS EN ISO 3382:2

(2008) are the Interrupted Noise Method or the Impulse Response Method. Both methods rely on

generating high level noise, which would generally be unacceptable in an occupied hospital ward.

It was decided that if an opportunity arose to make RT measurements in unoccupied patient

accommodation, then the Impulse Response Method should be used with a balloon burst as the

source. This was purely down to the logistics of carrying bulky equipment into a hospital.

Loudspeakers and amplifiers would be required if the Interrupted Noise Method was chosen, and this

was not practical.

Where the Impulse Response Method was used, the number of source and receiver positions

stipulated by British Standard BS EN ISO 3382-2 (1998) for ‘engineering’ work was adhered to with

RT20 values for octave frequency bands from 250 Hz to 4000 Hz reported. For this category at least

two source and at least two receiver positions were stipulated for each measurement.

Where on site RT measurement was not possible, an estimation method was used which made use of

‘level above’ trigger sound files. This is discussed in further detail in Chapter 10.

5.4. Questionnaire survey design

This section describes the design of the staff and patient questionnaires used in the study. Examples

of each questionnaire can be seen in Appendix A.


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5.4.1. Staff questionnaires

The first section entitled ‘About You’ was designed to categorise certain staff attributes by identifying

sex, age bracket, staff grade, length of service on the ward and at the hospital. The questions were

very general, without asking anything that could be deemed as too personal or intrusive. It was

thought that with a large overall dataset, these categories may help to establish relationships

between, for example, the length of service and noise annoyance.

The second section entitled ‘About Your Environment’ examined perceptions of noise annoyance and

noise interference with the ability to work. It was felt that it was important to not only examine noise

annoyance but also whether staff felt that their work was impacted by certain sounds. The

questionnaire sought to identify the sources of both annoyance and interference by providing a list of

noises (which were identified from initial observations made in the pilot study ward). Staff were asked

to rate the annoyance / interference of each noise source listed on a scale of 0 to 4 (where 0 indicated

no annoyance / interference and 4 indicated a great deal). Several lines were left blank at the bottom

of the lists for staff to add and rate additional noise sources.

The third section aimed to aid understanding of which sounds were felt by staff to be important in

order to carry out their jobs effectively. Staff were asked to rate the sounds on a scale of 0 to 4, where

0 indicated ‘not at all important’ and 4 indicated ‘extremely important’. Again, several lines were left

blank at the bottom of the lists for staff to add and rate additional sounds that they considered

important.

A comments section was left at the end of the questionnaire for any additional feedback.

5.4.2. Patient questionnaires

The first section entitled ‘About You’ was designed to categorise certain general attributes by

identifying sex, age bracket, length of stay on the ward and bed number. As with the staff

questionnaires the questions were very general, without asking anything that could be deemed as too

personal or intrusive. The following provides the reasoning behind this line of questioning:

� The sex of a patient may yield information regarding differences between men and women

regarding sensitivity to noise.

� The age group of the patient may be related to their sensitivity to noise, as hearing generally

deteriorates with age.

� How long a patient has been on the ward may indicate whether there is a correlation between

length of stay and becoming more acutely aware of noise, or whether an individual becomes

more used to the noise levels.


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42

� The patient’s bed number provides location information. Relationships may be shown to exist

between bed location and specific sources of noise.

The second section titled ‘About Your Environment’ considered noise annoyance both during the day

and at night. The questionnaire sought to identify the sources of noise that may annoy or disturb

patients. Respondents were given a list of noises (which were identified from initial observations

made in the pilot study ward), and were asked to rate the annoyance / disturbance on a scale of 0 to 4

(where 0 indicated no annoyance / disturbance and 4 indicated a great deal). Several lines were left

blank at the bottom of the lists for patients to add and rate additional noise sources.

The third section of the questionnaire contained a number of questions designed to investigate the

acoustic environment further, including perceptions of speech privacy. The following paragraphs

discuss the contents of this section further:

Sound was examined in a positive rather than in a negative light, with patients asked if there were any

sounds that they actually found comforting. Three blank lines were provided for a response.

Communication between nursing staff and patients was investigated, by asking patients whether they

could clearly hear what was said to them by the medical staff. The aim of this question was to

highlight high levels of background noise and poor acoustics, but of course a patient suffering from a

hearing impairment would have difficulty hearing for other reasons. To take this into consideration,

patients were also asked if they had a hearing impairment. It was felt that asking details of the

impairment would be deemed too personal, and so a ‘yes’ or ‘no’ response to this question was

provided.

Conversational privacy was investigated by asking whether a patient felt that they could have a

private conversation at their bedside. If the response was in the affirmative, a further question was

asked to see if the patient would feel comfortable speaking normally or whether they would need to

lower their voice or take some other precautionary measure.

Finally, respondents were asked if they felt that there was ever too little sound in a room. This

question was asked as some previous study findings suggest that patients may feel isolated if it is too

quiet.

A comments section was left at the end of the questionnaire for any additional feedback.

5.5. Preliminary work

5.5.1. Building relationships with hospitals and Healthcare Trusts

Following the agreement of the project proposal, meetings were held with estates staff at each of the

proposed locations. It was considered very important that the estates teams supporting the study felt

that it would provide them with useful data. Study feedback could potentially provide information on


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43

the current performance of the occupied buildings on site, and could be used to inform the design of

future site developments or refurbishments.

Feedback from the initial meetings was positive, and further meetings were held with the members of

the estates teams and senior clinicians to ascertain the best inpatient ward locations in which to

conduct the study at each site.

It was agreed that a pilot study would initially take place at Great Ormond Street Children’s Hospital. It

was felt that the study could yield useful information for the hospital’s redevelopment team about the

acoustics of the Octav Botnar Wing, whose design was heavily influenced by the need for infection

control, with hard, easily cleanable surfaces.

5.5.2. Ethics and Trust approval

Before any part of the study could be started, the necessary permissions needed to be granted by

each Trust. These permissions involved a personal police check of the researcher who would be

working at each site, and a statement of ethical approval from both the central NHS Ethics Service

and London South Bank University.

National Research Ethics Service

All proposed healthcare studies require a level of scrutiny by the National Research Ethics Service

(NRES). The advice published by the service is biased towards clinical trials and is hard to interpret.

Some short-term projects have failed entirely due to the length of time involved in granting ethical

approval.

After consulting with NRES, it became apparent that there would be no ethical issues surrounding the

proposed objective study, which would be viewed as an ‘audit’. However, ethical approval would be

required if staff and patients were to be interviewed. This would mean a very lengthy process waiting

for committee decisions.

Further discussion with NRES suggested that if, rather than interviewing staff and patients, an

anonymous questionnaire was used, submission to an ethics committee might not be required, with

the study being classed as ‘a service evaluation’.

A document was prepared explaining the planned use of staff and patient questionnaires. This

document along with details of the objective study, a poster advertising the study, staff and patient

information sheets and copies of the questionnaires were all submitted electronically to NRES. The

response classed the study as a ‘service evaluation’ and confirmed that a Research Ethics Committee

review was not required.

Copies of all documents mentioned above can be found in Appendix A.


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44

London South Bank University Ethical Review

Following the response from NRES, an application for ethical review was submitted to the Executive

Dean of the Faculty of Engineering, Science and the Built Environment at London South Bank

University.

The London South Bank University Code of Practice for Investigations on Human Participants deems

that ‘Class 1 Investigations are any investigation taking the form of a general survey / questionnaire /

interview (including telephone surveys) which do not involve the request or receipt of personal

information, as defined by the Data Protection Act 1998, from the participant’. The Code of Practice

states that Executive Deans may approve Class 1 Investigations providing these comply with this

Code of Practice.

It was felt that this study fell into the category of a Class 1 Investigation and as such the relevant

documentation was sent directly to the Executive Dean for review. Ethical approval from the

University was given forthwith and evidence is provided in Appendix A.

Hospital specific permissions

Once ethical approval had been received from NRES and London South Bank University and the

police checks had been finalised, temporary contracts of employment and security passes could be

issued by each Trust. The onsite study was then able to commence.

5.6. Conclusions

This chapter has described the design of the objective and subjective surveys, plus the preliminary

procedures that were necessary in order to carry out research in occupied hospitals. The following

chapter describes the pilot study that was undertaken to validate and further develop the methods

discussed in this chapter.

Acoustic Design for Inpatient Facilities in Hospitals Pilot Study

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45

6. Pilot Study

6.1. Introduction

A pilot study involving acoustic and questionnaire surveys was carried out in a post surgical inpatient

ward in a five year old building at Great Ormond Street Children’s Hospital, London. The aim of the

pilot study, which took place over a four month period from September to December 2009, was

twofold: to test the methodology to be used in the main study to ensure that meaningful results could

be obtained in line with the research proposal; and secondly, to provide useful feedback for the

redevelopment team and the ward manager on site. The design of this particular building was heavily

influenced by the need for infection control, with hard, easily cleanable surfaces. The redevelopment

team were interested to find out how the building performed acoustically post occupation, and

whether the design compromised this performance in any way.

Particular consideration was given to the following aspects of methodology to identify the optimal

dataset to be collected in the study and to ensure it would be as robust and reliable as possible.

� The choice of suitable microphone positions to allow for meaningful comparisons to be made

between patient accommodation types.

� Use of the ‘level above’ trigger functionality built into the sound level meter as a means of

identifying sources of high level noise.

� The choice of a representative measurement time interval.

� To check for ambiguous or misleading questions in the staff and patient questionnaires.

This chapter begins by looking at the background of Great Ormond Street Hospital for Children,

providing an overview of the acoustic design considerations of the study ward and exploring the

hospital policies and equipment usage that may affect noise levels. The chapter continues by

considering the most effective ways of positioning the measurement equipment and also ensuring

adequate publicity of the study. Objective results from each ward are reported, and staff and patient

perceptions of the noise environment are explored. The results of the study were reported back to the

ward staff in several meetings; their observations on the findings and possible actions are discussed

at the end of this chapter.

6.2. Background

Great Ormond Street Hospital for Children (GOSH) was established in 1852, and was first located at

49 Great Ormond Street, London. With its motto “the child first and always”, the hospital has become

the leading UK tertiary paediatric hospital, providing the widest range of specialist paediatric services

in the country.


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46

As part of an ongoing redevelopment plan for the site focusing on the delivery of a new model of care,

the construction of The Octav Botnar Wing was completed in early 2006, and is shown in Figures 6.1

and 6.2. This building was designed to provide a unique, uplifting environment for both patients and

staff by maximising the use of natural light, bright colours, and innovative designs. The Octav Botnar

Wing houses a number of specialist centres including an International Patient Centre; Medical Day

Care Centre; Orthopaedic Ward and Biomedical Engineering Centre.

Figure 6.1 Figure 6.2

The Octav Botnar Wing Main entrance to the Octav Botnar Wing

6.3. Sky Ward

Out of the four specialist centres situated in the Octav Botnar Wing, only the orthopaedic ward (known

as Sky Ward) fitted the research project criterion of general inpatient care. Length of stay here is

generally from one day to two weeks, with patients undergoing a number of different types of surgery

including limb lengthening procedures, and spinal, hip and foot surgery. Patient ages vary from

infancy up to 18 years of age.

The new clinical facilities were designed to provide greater space for patients, more comfortable

surroundings for a parent to stay by their child’s bedside and more efficient use of space for nursing

teams. The ward is built on a "racetrack design" that positions patient rooms on the outer part of each

floor and locates the health care resources in the centre of the building. Consisting of three 4-bed

bays and six single patient rooms, there are a total of 18 patient beds. Rooms facing east and south

include floor to ceiling glazing looking out onto a balcony area (which is locked and not available for

use). Rooms facing west have smaller areas of glazing. All 4-bed bays and single rooms have ensuite

shower and toilet facilities. Each patient bed also has its own flat screen television, hoist, and a bed

for parents to sleep next to the patient (the single rooms have a pull down bed; the 4-bed bays have

chairs which convert to beds). Figure 6.3 shows the brightly coloured ward reception area, and Figure

6.4 shows a patient bed in a 4-bed bay.


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47

Figure 6.3 Sky Ward reception Figure 6.4 Typical four bed bay

Healthcare resources are situated in the centre of the ward and include a clean and dirty utility room;

a plaster room; a sensory room; kitchen; assisted bathroom; equipment store; adolescent room; ward

manager’s office; and two nurse stations. A plan of the ward is shown in Figure 6.6 on page 51.

6.4. Building acoustic design considerations

The Octav Botnar Wing was built to conform to the Health Technical Memorandum HTM 2045:

Acoustics Design Considerations (NHS Estates, 1996), which contained partition performance

requirements as well as advice on many other aspects of acoustic design (as discussed in Chapter 2).

It was therefore assumed that floors, walls, windows and doors were of a reasonable specification in

terms of sound insulation and sound attenuation.

6.4.1. Nurse stations and common areas

Within the corridors and around the nurse stations there was no visible acoustic absorbency. The

ceilings at the nurse stations were solid plaster with round inspection hatches to access services. The

corridor ceilings were also solid plaster with a strip of metal ceiling tiles running down the centre to

provide access to services. Floors were heavy duty vinyl and walls were plasterboard on a metal grid

system.

6.4.2. Patient accommodation

The 4-bed bays and single patient rooms all had suspended ceiling grids with Armstrong Ultima

ceiling tiles. The properties of these tiles are shown in terms of their sound absorption coefficients (α)

at different frequencies in Figure 6.5.


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48

Figure 6.5 Ultima ceiling tile sound absorption coefficients (α) over a range of frequencies

Source Manufacturer’s datasheet

All patient accommodation has vinyl flooring and plasterboard walls mounted on a metal grid system.

Additional acoustic absorbency is provided by window curtaining, upholstered upright chairs, patient

and parent beds and privacy curtaining that can be pulled around each bed (4-bed bays only). Full

length curtains are also provided to pull around the parent bed in the single patient rooms for

additional privacy.

6.5. Ward routines

The ward manager of Sky Ward was enthusiastic and supportive of the study. He had some concerns

about several of the systems in place on the ward which he considered to be excessively loud. It was

decided that an investigation of these systems could be easily incorporated into the study.

To help inform the study design, some time was spent on the ward to build up an appreciation of ward

layout, to meet the staff and to make on-the-spot sound level measurements. Several discussions

with the ward manager helped to build up an understanding of the day-to-day running of the ward and

any events that could potentially affect the noise levels. This initial discussion process was found to

be useful and was used throughout the main study.

Information and events which were thought be of some significance are discussed in the following

sections.

6.5.1. Staffing and patient levels

Due to the nature of care in this particular ward, and the timings of the operations, staffing levels and

ward occupancy are generally at their highest during weekdays. Weekday staffing levels generally

consist of between three and five clinically trained staff, up to three students and up to two health care

assistants for a day shift, with fewer staff at night.

During a weekend, ward occupancy rates drop to less than 50%, staffing levels are lower and often

one 4-bed bay and several single rooms are left empty.


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49

Due to this drop in occupancy, it was decided that measurements made during the weekends would

not be representative of the typical use of the ward and it was therefore decided that analysis would

only be carried out on weekday measurements for the pilot study.

6.5.2. Staff shift patterns and ward rounds

Staff day shifts start at 07.45 and end at 20.15, with night shifts starting at 19.45 and ending at 08.15.

There is a 30 minute shift overlap between 07.45 and 08.15 and 19.45 and 20.15 with potentially

more staff gathered at the nurse stations for handover sessions. Higher levels of noise may be

attributed to these changeover periods.

Ward rounds generally start around 08.15 (after the completion of the shift handover), with many of

the children on the ward requiring hourly checks by medical staff.

6.5.3. Cleaning

Cleaning usually begins at 08.00. Daily cleaning generally consists of a felt floor mop to remove dust

(floors are buffed once every two weeks); the emptying of the two rubbish bins in each of the bays

and single rooms twice daily (general and chemical waste); the cleaning of the ensuite bathrooms;

and bed changing.

6.5.4. Meal times

Meal times are at 12.00 and 17.00 and last approximately one hour. Meals are individually served to

patients, with no meal round with a trolley. It was felt that it was unlikely that noise levels would be

impacted greatly by the serving of meals to patients.

6.5.5. Medical equipment with alarms

Three types of medical equipment are used on the ward which may contribute to noise levels:

� The fluid pump. This has a high pitched alarm if intervention is required.

� Heart rate and oxygen level monitor. This has a lower pitched ‘bong’ alarm if intervention is

required.

� A nebuliser which creates a mist of medicine which is breathed in through a mask or

mouthpiece. This is commonly used to give high doses of reliever medicine and when in

use makes a low level ‘bubbling’ sound.

6.5.6. Access to patient accommodation

All doors to the 4-bed bays are left open both day and night for staff observation. This is how the staff

at this hospital are trained to care for patients in multi-bed accommodation. If doors to a bay are shut,

it is assumed that there are no patients present.


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50

The doors of the single patient rooms are generally left open during the day (depending on the

patient’s preference and condition), but closed at night if there is a relative staying with the patient.

Patients given single room accommodation are generally infants under one year old, those with

special medical needs or infectious patients. Staff are happy for the doors to single rooms to be

closed if a patient is infectious or if the parent is with the child and can call for help if the need arises.

6.6. Measurement locations

It was considered important that the measurement locations chosen were those that could be easily

repeated within the main study and that the locations reflected the study aim: to build up a

comprehensive picture of noise levels in inpatient care. Figure 6.6 shows the ward layout which is

discussed further in the following sections.

6.6.1. Nurse stations

There were two nurse stations on the ward and these were located at either end of the central

healthcare resource block. It was felt that for comparison purposes it was important to measure noise

levels at both.

Nurse station 1 was closest to the ward entrance at the junction of several corridors. One corridor

provided access to the ward manager’s office and ward reception, with the other corridor running

down the length of the ward. A 4-bed bay was located opposite this nurse station. As the doors to this

bay were always left open, patients could potentially be affected by noise from the nurse station.

Figure 6.7 shows the nurse station, and Figure 6.8 shows the corridor running to the ward manager’s

office and ward reception.

Figure 6.7 Nurse station 1 Figure 6.8 Internal corridor

Microphone Position

Single Patient Room A

Nurses’ Station 2

Single Patient Room B 4 Bed Bay B

4 Bed Bay A

Nurses’ Station 1

Ward Entrance

Reception Desk

Waiting Area

Figure 6.6 Layout of Sky Ward with microphone positions


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52

The nurse station was a semicircular desk with a number of drawers, on which a computer,

printer, telephone, security monitor and the nurse call control panel were installed, as shown

in Figure 6.9. There was a small grill on the wall behind the desk covering the loud speaker

to which the nurse call system and doorbell were piped. This loud speaker can be seen

labelled in Figure 6.10.

Figure 6.9 Internal telephone & security monitor Figure 6.10 Wall mounted speaker grill

Nurse station 2 was much larger than its counterpart and tended to be busier, with more staff.

It was located at the opposite end of the ward to nurse station 1, with two single patient rooms

directly opposite and a 4-bed bay to the right. Due to the open door observation policy the 4-

bed bay could be potentially affected by noise from the nurse station. To either side of the

nurse station were sets of double doors but these were left open at all times, except in the

event of fire, when they would automatically be closed.

As with nurse station 1, this location was a semicircular desk with a number of drawers, on

which several computers, a printer, a telephone, security monitor and the nurse call control

panel were installed. This can be clearly seen in Figures 6.11 and 6.12. Again there was a

small grill on the wall behind the desk covering the loud speaker to which the nurse call

system and doorbell were piped. Patient notes were kept in ring binders and there were often

a number of ring binders laid out on the top of the desk.

Speaker grill


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53

Figure 6.11 Nurse station 2 Figure 6.12 Nurse station 2 desk

6.6.2. Four bed bays

Two different 4-bed bays were chosen for comparison purposes. The rooms were different

shapes, had different bed positioning and differing amounts of glazing. Identical facilities were

available for patients.

4-bed bay A faced out onto nurse station 2 and was accessed through a set of open double

doors. To the left hand side of the ward entrance was a hand washing sink and two rubbish

bins for chemical and general waste. There were two beds positioned on the left hand side of

the room and two on the right. Each patient bed could be ‘curtained off’ from the ward, which

was often the case when the bed was occupied, presumably for reasons of privacy. Parents

were provided with a chair which converted to a bed so that they could sleep next to their

child at night. At the back of the bay were floor to ceiling windows and a glazed door opening

out onto the balcony area. The windows and door did not open; this bay was mechanically

ventilated only. In the back right hand corner a set of metal lockers were provided for parents

to store valuables, next to which was the door to the ensuite shower room.

4-bed bay B (shown in Figure 6.13) was situated at the opposite end of Sky Ward facing the

smaller of the two nurse stations. Unlike bay A, this bay was ‘L’ shaped, with two beds

situated on the right hand side of the room and two beds on the back wall. This room was

both mechanically and naturally ventilated, with openable windows. As with bay A, the bay

was accessed through a set of double doors, which were left open at all times. To the left of

this entrance were two rubbish bins for chemical and general waste, and round the corner

was a hand washing sink, door to the ensuite shower room and lockers provided for storage

of valuables, as can be seen in Figures 6.14 and 6.16. All the same patient and carer facilities

existed in both bay A and bay B, including flat screen televisions for each bed and patient

hoists. Figure 6.15 clearly shows these patient facilities.


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54

Figure 6.13 4-bed bay B

Figure 6.14 Hand washing sink, door Figure 6.15 Patient bed and fold

to shower room and lockers down chair

Figure 6.16 Ward entrance with rubbish bins


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55

6.6.3. Single patient rooms

Two different rooms were chosen for measurements. The rooms were situated on different

sides of the building and were slightly different in terms of room design and the amount of

glazing used.

Single patient room A was opposite nurse station 2. This room was mechanically ventilated

only and had full length windows and a patio door looking out onto a balcony area. As with

4-bed bay A, the windows and door could not be opened. The room had its own ensuite

shower and toilet, and a pull down bed was provided for the child’s parent. For privacy

purposes, full length curtains could be pulled around this bed. Separate curtaining was

provided to cover the external windows and patio door and also block out the light shining

through the glazed panel of the door to the corridor. To the left hand side of the room was a

hand washing sink and two rubbish bins for chemical and general waste. Several upright

chairs were available for visitors and an easy chair next to the bed for patient or parent use.

Figures 6.17, 6.18 and 6.19 show the bed head services, glazed balcony door, and pull down

bed with the room sink and rubbish bins.

Figure 6.17 Patient bed showing bed head services

Figure 6.18 Locked door onto balcony Figure 6.19 Door to ensuite, pull down

bed, sink and rubbish bins

Flat screen

television

Patient hoist


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56

Single patient room B was located halfway down one of the main ward corridors, opposite the

dirty utility room and the assisted bathroom. This room was mechanically ventilated, but

unlike room A, the windows could also be opened. Room B was slightly smaller in area than

room A, but had the same facilities available for patients and their carers including a pull

down bed, flat screen television and a patient hoist, which could be used to hoist the patient

out of bed and as far as the ensuite shower room if necessary. Figures 6.20, 6.21, 6.22 and

6.23 show the patient bed, sink and rubbish bins, the pull down bed and the patient hoist in

room B.

Figure 6.20 Patient bed and opening windows Figure 6.21 Rubbish bins and hand

washing sink

Figure 6.22 Pull down bed Figure 6.23 Flat screen television

6.7. Equipment and microphone positioning

Apart from the issue of cleanability, which was discussed in Chapter 5, care was taken over

the positioning of the microphone and associated equipment so as to minimise its impact on

staff duties and patient care. It was decided that to record comparable noise levels the


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57

microphone should be located in similar positions in similar locations (e.g. similar positioning

in two single rooms). Figure 6.6 shows the ward layout and microphone positions which are

discussed in the followed sections.


As the nurse stations were busy areas, it was important that the microphone was positioned

where it was not likely to be knocked, and yet could collect comparable measurement data. In

both cases the microphone was placed on a shelving unit, 2.1 m high, pointing down at the

nurse station. The microphone position is shown by the star symbol on Figures 6.24 and 6.25.

Figure 6.24 Microphone position at Figure 6.25 Microphone position at

nurse station 1 nurse station 2

6.7.2. Four bed bays

The four bed bays presented more of a problem regarding microphone positioning. It was not

possible to position the measurement equipment close to a bed head, as there was too much

medical apparatus situated there. It was also felt by the ward manager that the patient / family

would find having the microphone so close rather intrusive. Another consideration was that

when moving the beds, equipment would easily be knocked and potentially damaged.

As measurements were to be made in two 4-bed bays, it was also necessary to find a position

in each ward that would yield comparable sets of measurements. A set of lockers 2 m high,

which were used by the parents for storage of valuables, were identified as a possible

location. These lockers, shown in Figure 6.26, were located at the back of each ward next to

the ensuite bathroom door and offered a comparable position in each bay.


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58

Figure 6.26 4-bed bay B with microphone placed on top of lockers


As with the 4-bed bays it was not practical to position the microphone close to the bed head.

A fixed cupboard housing the parents’ pull down bed was identified as a comparable location

in each room. As shown in Figures 6.27 & 6.28, the microphone was positioned 2 m from the

ground pointing down into the rooms.

Figure 6.27 Single patient room 1 Figure 6.28 Single patient room 2

with microphone position shown with microphone position shown

6.8. Other considerations

6.8.1. Identifying the optimal ‘level above’ setting for trigger files

As discussed in Chapter 5, the use of observers to identify sources of high level noise was

not practical in this study. An alternative method of identification was to make use of the built

in ‘level above’ trigger functionality of the sound level meter which creates a short audio file


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59

each time the LAmax parameter exceeds a specified threshold. Once the data is transferred to

a PC for analysis, each audio file can be reviewed and the sources of the high level noise

identified.

To determine the settings needed for the optimal use of this feature, various threshold and

audio quality settings were tested during the first measurement periods. Due to the limited

storage capacity of the sound level meter (2 Gb) it was important that the number and the

size of the trigger files created did not exceed this capacity before the completion of the

measurement period. If this did occur the sound level meter would simply stop part way

through a five day measurement period, resulting in a loss of data. After some

experimentation, a threshold of 70 dB LAmax was found to be the most workable setting, which

meant that each time the value of LAmax exceeded 70 dB an audio file was created. Further

detailed technical information on the use of trigger files can be found in Section 10.2.

6.8.2. Publicising the study

Some weeks before the study commenced, five laminated advertising posters were displayed

throughout the ward common areas. These posters explained in simple terms why and how

the study was being undertaken, and were aimed at both staff and parents / patients. In

addition to these posters the ward manager personally discussed the study with all his staff

during staff meetings.

It was felt that it was of utmost importance that as much information as possible was

provided. This would help to avoid any unnecessary suspicion or animosity once the

microphone was visibly introduced into the ward environment. If staff and parents / patients

were informed some time before the equipment was introduced, it was unlikely that their

behaviour would change as a result (known as the Hawthorne Effect, discussed in Section

3.2.1), as they would fully understand the reasons for the study and not feel under scrutiny

themselves.

A copy of the publicity poster can be seen in Appendix A.

6.8.3. Reverberation time measurements

As occupancy levels in Sky Ward reduced during the weekend, leaving several single rooms

and one 4 bed bay empty, it was possible to take advantage of this and make some

reverberation time measurements using an Impulse Response Method with balloon bursts as

the source. Measurements could not be made in the common areas such as nurse stations

and hallways, as the ward was still occupied in part and this would have disturbed both staff

and remaining patients.


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60

6.9. Questionnaire survey considerations

Information sheets and questionnaires were handed out to the staff on an ‘away day’ out of

the ward. This was suggested by the ward manager as it was thought that this approach

would yield the best response rate. The sample set for the staff study was fairly small, as the

total number of full time staff working on this ward was only 12. Every full time member of

staff completed the questionnaire survey.

Many of the children on this ward were too young to complete the questionnaire themselves.

After discussion with the ward manager, it was decided that the questionnaires would be

given to the accompanying parents, who were given the option of completing the

questionnaires on their own or jointly with their child (age and medical condition permitting). It

was felt important that the parent / patient had been present on the ward for over 24 hours to

give sufficient time for the individual(s) to form an opinion of the noise environment during the

day and the night. The first section of the patient questionnaire was changed slightly to

capture information about both the parent and patient, with an additional question to establish

whether the parent completed the questionnaire with or without input from their child.

The patient information sheets and questionnaires were handed out by the ward clerk to the

parents of the patients on the ward. In total 31 completed parent / patient questionnaire

responses were received.

Copies of the patient / parent and staff questionnaires are shown in Appendix A.

6.10. Overall acoustic survey results

Table 6.1 shows the locations and the time periods of all measurements made. It should be

noted that ‘1 week’ is defined as one set of week day data (Monday to Friday), weekends

having been excluded from the measurement period for the reasons given in Section 6.5.1.

Table 6.1 Measurement location and time interval

Position Length of measurement period

Nurse station 1 2 consecutive weeks (10 days)

Nurse station 2 1 week (5 days)

4-bed bay A 2 consecutive weeks (10 days)

4-bed bay B 1 week (5 days)

Single room A 1 week (5 days)

Single room B 1 week (5 days)

Overall noise measurements of A-weighted equivalent sound pressure levels (LAeq) for 24

hours, day time and night time were recorded, the day and night periods being defined by the

WHO guidelines (Berglund et al, 1999), where day time is specified as 07.00 to 23.00 and


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61

night time as 23.00 to 07.00. Table 6.2 shows the average LAeq measured for 24 hour, day

and night time periods at each location.

Table 6.2 Average LAeq measured for 24 hour, day and night time periods at each location

Position in ward Weekday average of A-weighted equivalent sound pressure levels

24 hours Day time Night time

LAeq, 24hr LAeq, 16hr LAeq, 8hr

Nurse Station 1 Week 1 56.6 58.3 47.2



4-Bed Bay A Week 1 50.2 51.7 43.4

4-Bed Bay A Week 2 52.3 54.0 41.9

4-Bed Bay B 50.4 52.2 39.5

Single Patient Room A 50.4 52.2 34.8

Single Patient Room B 56.6 58.2 47.8

A summary of the day and night time average levels (averaged over all the measurement

days for each location) are presented in Table 6.2 are presented graphically in Figure 6.29 for

clarity. It can be seen that without exception, all levels exceed those suggested in the WHO

guidelines (30 dBA LAeq for day and night). Levels measured at the nurse stations and in the

4-bed bays are shown to be fairly consistent, with night time levels on average 10 dB lower

than those measured during the day. Single patient rooms, however, are much less

consistent during both the day and night. Detailed results of levels measured at the nurse

stations are discussed in the next section, with further results from the 4-bed bays shown in

Section 6.12 and from single patient rooms in Section 6.13.


__________________________________________________________________________________________________________

62

0

10

20

30

40

50

60

70

Nurse Station 1 Nurse Station 2 Single Room A Single Room B 4 Bed Bay A 4 Bed Bay B

So

un

d P

ressu

re (

dB

A)

Day time

Night time

Figure 6.29 Average day and night LAeq levels measured at each location

6.11. Nurse stations

Figure 6.30, shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours at the two nurse

stations (means of total number of measurement days). It can be seen that the levels at nurse

station 2 are consistently higher than those measured at nurse station 1. This is as we would

expect as this nurse station is significantly larger in size, with more staff working in this area.

The levels follow very consistent patterns suggesting that the daily ward routines which

contribute to the noise levels are similar at both locations.

Interestingly, background levels at night (shown in terms of LA90,1hr) are slightly lower for nurse

station 2, even though the LAeq,1hr levels are higher at this nurse station. This could be affected

by the level of airflow from the mechanical ventilation system. Although controlled centrally in

the ward, noticeable differences were found between levels of airflow in different ward

locations. This is discussed further in Section 6.15.2.


__________________________________________________________________________________________________________

63

30

40

50

60

70

So

un

d P

ressu

re (

LA

eq

, 1

hr)

Time (24h:00)

Nurse Station 1 LAeq Nurse Station 2 LAeq Nurse Station 1 LA90 Nurse Station 2 LA90

Day timeNight time

Figure 6.30 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse stations

6.11.1. Sources of high level noise

As discussed in Section 6.8.1, sources of high level noise were identified from the trigger files

captured by the sound level meter during the measurement period. The threshold for this data

capture was set to 70 dB LAmax. By reviewing each file it was possible to build up an

understanding of the types of high level noise sources present, and, by analysing the data

further, understand the impact of a particular noise event on the average noise levels.

A summary of high level noise sources identified at the nurse stations is given below:

� Staff to staff conversation

� Staff talking on the telephone

� Staff talking with patients

� Patients talking

� Ward doorbell

� Nurse call

� Internal telephone ringing

� Patients crying out

� Desk drawers

� Footsteps

� Laughter

� Furniture scraping on the floor

� Coughing

� Replacing the telephone receiver

� Medical equipment alarms

� Mobile phones ringing

� Closing ring binders

The ward manager was particularly interested in capturing occurrences of a number of ward systems

which were considered to be excessively loud. The nurse call system, internal telephone and the door

bell were all cited. Trigger files collected at the nurse stations were analysed to find the average

maximum levels of these systems. This data was captured during the first three weeks of the pilot

study and in some cases was incomplete due to initial equipment configuration problems. However,


___________________________________________________________________________________________________________________

64

enough data was collected to provide a good indication of the true levels of these systems. This is

discussed further in the following paragraphs.

Nurse call

When a patient presses the nurse call button by their bed, a light flashes outside their bay or room, a

tone is emitted through the speaker behind each nurse station and information is displayed on the

console on the nurse station desk, as shown in Figure 6.31. The tone continues until the nurse

attends to the patient and cancels the call by the bedside.

Figure 6.31 Nurse call console

The microphone at nurse station 1 was positioned 3 m from the wall speaker. The levels and number

of occurrences of the nurse call which created trigger files were noted and the maximum levels were

arithmetically averaged over the five day measurement period. The distribution of the LAmax levels is

shown in Figure 6.32. In total there were 115 instances of the nurse call tone captured, resulting in an

average maximum value of 81.3 dB LAmax. The highest percentage (45%) of occurrences fell into the

LAmax level category of 82 to 84 dB. There was no noticeable difference between the levels measured

during the day or night, which was interesting as it was thought that the system had a night time

setting which lowered the volume of the tone emitted.

0

10

20

30

40

50

60

72 - 74 74 -76 76 -78 78 - 80 80 - 82 82 - 84 84 - 86

Nu

mb

er

of

occ

ure

nce

s

LAmax range (dB)

Figure 6.32 The number and levels (LAmax) of occurrences of the nurse call system at nurse

station 1, measured at 3 m over 5 days


___________________________________________________________________________________________________________________

65

Only a small amount of data was available for review from nurse station 2. In total 13 instances of the

nurse call were captured over a 19 hour period, again with the microphone positioned 3 m away from

the wall speaker. An average maximum value of 80.2 dB LAmax was calculated. The highest

percentage (54%) of occurrences fell into the LAmax level category of 82 - 84 dB as with nurse station1.

Internal Telephone

The microphone at nurse station 1 was positioned 3 m from the telephone on the desk. Over the five

day measurement period there were ten separate occurrences of the ringing telephone which created

trigger files. The resulting average maximum of the internal telephone was found to be 72.3 dB LAmax.

As the average maximum was close to the trigger threshold of 70 dB LAmax, it is felt that some

occurrences of the ringing telephone may not have been captured, so as such this figure may not be

accurate.

No data exists for the internal telephone at nurse station 2, but it is expected that similar levels would

have been measured.

Ward Doorbell

When the ward reception desk is unmanned, ward visitors ring the doorbell and a member of staff

remotely opens the door to the ward, which is locked for security purposes. As with the nurse call, the

ward doorbell is piped to the small speaker mounted behind each nurse station.

Only a small amount of data was available for review in this case. This was for nurse station 2 with

the microphone positioned 3 m from the speaker. In total, 42 instances of the doorbell were captured

over a 19 hour period, resulting in an average maximum value of 80.6 dB LAmax. The highest

percentage (52%) of occurrences fell into the LAmax level category of 80 to 82 dB. The distribution of

the LAmax levels is shown in Fig 6.33.

0

5

10

15

20

25

74 -76 76 -78 78 - 80 80 - 82 82 - 84 84 - 86

Nu

mb

er

of

occ

ure

nce

s

LAmax range (dB)

Figure 6.33 The number and levels (LAmax) of occurrences of the ward doorbell at nurse station 2,

measured at 3 m over 19 hours


___________________________________________________________________________________________________________________

66

Although data was only available from nurse station 2, it is expected that similar levels would have

also been measured at nurse station 1.

All the reported levels for the three ward systems are typical of those to which a staff member would

be exposed when sitting at the nurse station desk. Figure 6.34 illustrates the difference between

these calculated maximum levels and the average day and night time levels measured at the nurse

stations. It can be seen that the average LAmax levels exceed the day time LAeq,16hr by between 14 and

23 dB, and the night time LAeq,8hr by between 24 and 33 dB.

30

35

40

45

50

55

60

65

70

75

80

85

90

Nurse Call Internal Phone Doorbell

So

un

d P

res

su

re (d

BA

)

80.6 dB LAmax80.8 dB LAmax

72.3 dB LAmax

Figure 6.34 Average LAmax of the nurse call system, internal telephone and ward doorbell

When questioned, staff cited the ward doorbell, nurse call and internal phone as the most annoying

sources of noise (see Section 6.16.2). Staff also rated these systems as the noise sources which

most interfered with their ability to carry out their job effectively.

6.12. Four bed bays

Figure 6.35 shows the averaged LAeq,1hr and background levels (LA90,1hr) levels over 24 hours for the

two 4-bed bays. It can be seen clearly that the averaged LAeq,1hr levels were very consistent over time,

with a day time level of around 53 dB LAeq,16hr, over 20 dB higher than the WHO guidelines. The night

time average was found to be 11 dB lower than that measured during the day, around 42 dB LAeq,8hr.

This was still over 10 dB higher than the acceptable level stated in the WHO guidelines. Surprisingly,

there is a 5 dB discrepancy in background levels between the two bays during the night. This can be

partly explained because of the ventilation systems in use on the ward. Bay A is mechanically

Average day time level at nurse station: 58.2 dB LAeq,16hr

Average night time level at nurse station: 48.3 dB LAeq,8hr


___________________________________________________________________________________________________________________

67

ventilated only, and in bay B the windows can also be opened. It is possible that opened windows

may account for part of this discrepancy.

The figure also shows that the WHO day / night division is a poor fit, with noise levels tailing off earlier

in the evening, at around 21.00. This of course could be attributed to the fact that this is a children’s

ward and as such a day and night division specifically for a ward of this type may be more

appropriate.

20

30

40

50

60

70

So

un

d P

res

su

re (L

Ae

q,1

hr)

Time (24h:00)

4 Bed Bay A LAeq 4 Bed Bay B LAeq 4-Bed Bay A LA90 4-Bed Bay B LA90

Day timeNight time

WHO GUIDELINES

Figure 6.35 Average LAeq,1hr and LA90,1hr levels over 24 hours for 4-bed bays A and B


The sources of high level noise were identified from the trigger files captured by the sound level meter

during the measurement periods. The overall numbers of files for the three periods were similar, with

942 and 1002 files recorded in 4-bed bay A during measurement weeks 1 and 2 respectively, and 870

recorded in 4-bed bay B.

Building up a full picture of the sources of high level noise by reviewing the trigger files was at times

difficult. Many of the sources were fairly close to the microphone making it hard to build up a complete

picture of what was happening in the bay. As will be seen in Section 6.13 this was not the case in the

single rooms, where it was possible to identify some patterns with only one patient and parent

present.

Figure 6.36 shows the numbers of occurrences of each noise source type as a percentage of the total

number of files captured. It can be seen that for each measurement period a high percentage of

trigger files were listed as ‘unidentified’. These were commonly caused by visits by a clinician to a

patient. Often these visits were to provide patients with their medication; to undertake medical

examinations; or to redress wounds. During this time bed rails were moved and beds were readjusted


___________________________________________________________________________________________________________________

68

and repositioned, leading to the creation of a number of trigger files which were very difficult to identify

accurately. With younger patients especially, a visit by a clinician often led to a great deal of

screaming or crying. Patients were then made comfortable, leading to another set of high level noises

which were again difficult to identify and categorise. On occasions it was obvious that certain noise

events were related to a patient procedure, and were noted as such; however this was not always the

case.

Specific high level noise events which were clearly identifiable in these two bays were the door to the

ensuite facilities in 4-bed bay A (because of the loud locking mechanism); medical equipment alarms;

patients crying out; conversation; coughs and sneezes; and the use of rubbish bins, both in the

ensuite shower room and on the ward.

0 10 20 30

Unidentif iable

Conversation between staf f

Conversation between staf f and parents

Cough / sneeze

Dustbin

Laughter

Crying

Curtains

Parents / patients talking

Medical Equipment

Furniture Scraping

Squeak of shoes on f loor

Desk drawers / cupboard doors

Cleaning

Meal time

Visiting time

Door to ensuite bathroom

Patient procedures

Accessing lockers

Patient vomiting

Parent shouting for nurse

Children's entertainer

4 Bed Bay A Week 1 4 Bed Bay A Week 2 4 Bed Bay B

Figure 6.36 Percentages of high level noise events by type measured in 4-bed bays A and B

Figure 6.36 shows that particularly large differences can be seen between the percentages of trigger

files created over the measurement intervals in the two bays, especially those caused by patient

procedures, medical equipment and patients crying. All these are of course dependent on the severity

and type of the patient’s condition. Patients in Sky Ward undergo different levels of surgery and as

such it is not surprising to find large variation in the numbers of occurrences of high level noise

events.

There are notable differences in the use of the door to the ensuite bathroom from week 1 to week 2 in

4-bed bay A. The use of the ensuite may be related in part to the mobility of the patients and also to

the numbers of parents staying on the ward, so these factors may account for the change.


___________________________________________________________________________________________________________________

69

As discussed earlier in this section, many of the trigger files categorised as ‘unidentified’ are as a

result of visits by clinicians. It is interesting to note that the week with the highest percentage of

unidentified trigger events is the week with the highest percentage of medical equipment alarms and

patient procedures, suggesting more clinical activity on the ward during this week.

Surprisingly, trigger files caused by visiting time are only captured during week 2 in 4-bed bay A. On

reflection, this may be very dependent on the location of the microphone. Only visitors to the bed

situated next to the microphone are likely to cause noise of a sufficient level for the trigger files to be

created.

6.13. Single patient rooms

Figure 6.37 shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours for the two single patient

rooms. It can be seen that, unlike the 4-bed bays, the levels in the two single patient rooms were very

inconsistent, with an average difference in the LAeq levels of 6 dB during the day and 13 dB at night.

The night time background levels in single room B can be seen to be low, at around 29 dB LA90,1hr,

around 5 dB less than for single room A. This may suggest differences in the consistency of airflow of

the mechanical ventilation system, which is discussed further in Section 6.15.2.

The dotted line indicates the WHO specified average noise level for ward accommodation. It can be

seen that the night time levels in single patient room A were close to the recommended WHO levels,

but levels at other times were much higher, with a day time average LAeq,16hr of 58.2 dB in single room

B; almost 30 dB higher than the WHO recommendations.

20

30

40

50

60

70

So

un

d P

ressu

re (

LA

eq

, 1

hr)

Time (24h:00)

Single Room A LAeq Single Room B LAeq Single Room A LA90 Single Room B LA90

Day timeNight time

WHO GUIDELINES

Figure 6.37 Average LAeq,1hr and LA90,1hr levels over 24 hours for single patient rooms A and B


___________________________________________________________________________________________________________________

70

The next section looks at the sources of high level noise in each room in an attempt to understand the

inconsistencies found.


By identifying the sources of high level noise from the trigger files, it was possible to build up a picture

of the type of events which caused the measured levels to be so different between the two single

rooms. Figure 6.38 shows the percentages of each noise source type as a percentage of the total

number of files captured.

The overall numbers of high level noise events in each room were very different. There were nearly

five times more recorded high level noise events in room B (2898) than room A (608). This can be

explained in part by the severity and type of the patient’s condition. The patient occupying room B for

the majority of the measurement period required a large amount of clinical intervention during their

stay which resulted in 35% of all high level noise events being attributed to medical equipment alarms

and 16% to patient procedures (visits by clinicians to provide a level of care).

It can also be seen that the use of televisions and mobile phones caused a number of high level noise

events in room B, but not in room A. During the measurement period in room B there were 124

instances (4%) where the television level was greater than 70 dB, and there were 224 instances (8%)

where conversations on mobile phones were measured at this level or above.

0 5 10 15 20 25 30 35

Unidentif iable

Conversation between staf f

Conversation between staf f and …

Cough / sneeze

Dustbin

Laughter

Crying

Parents / patients talking

Medical Equipment

Furniture Scraping

Cleaning

Meal time

Visiting time

Talking on mobile phone

TV

Patient procedures

% occurance of event type

Single Patient Room B Single Patient Room A

Figure 6.38 Percentages of high level noise events by type for single patient rooms A & B

To illustrate the impact of certain high level noise events on the average noise level within a room,

certain typical events in single patient room A were analyzed in further detail. Table 6.3 presents the


___________________________________________________________________________________________________________________

71

event LAeq and LAmax. To put these levels into context the day time average noise levels measured in

this bay were 52.2 dB LAeq,16hr.

Table 6.3 Average and maximum noise levels of identified events in single room A

LAeq LAmax

Fluid Pump

Alarm71.6 89.1 19.4 36.9

Room Cleaning 54.4 79.3 2.2 27.1

Visit to a patient 57.6 75.7 5.4 23.5

Bin Bag

Changing60.4 75.5 8.2 23.3

Patient

Procedure59.2 81.5 7.0 29.3

Rubbish Bin Impulsive 80.6 Impulsive 28.4

Event (dB)Level above room day time LAeq

Event LAeq Event LAmax

It must be stressed that the events in Table 6.2 are shown for illustration purposes. They are not

necessarily representative of every event of that type. However, it is interesting to see that the

maximum noise levels measured were as high as 89 dB LAmax. Both the fluid pump and the rubbish

bins caused levels which were over 80 dB LAmax and exceeded the average day time noise level by

nearly 30 dB.

6.14. Establishing a representative measurement interval

One aim of the pilot study was to establish a representative measurement period which could then be

used throughout the main study. Many reviewed studies measured noise levels for a single 24 hour

period. It was considered unlikely that a randomly chosen 24 hour interval would be representative of

typical noise levels on a hospital ward. This is further illustrated by Figure 6.39 which shows the

noise level fluctuations over 24 hours for five days at nurse station 1. It can be seen that if, for

example, Thursday had been chosen for a 24 hour measurement interval, it would have yielded very

different results than if Tuesday had been chosen. In fact there would be a difference of 5.4 dB during

the night time LAeq,8hr and 5 dB difference during the day time LAeq,16hr.


___________________________________________________________________________________________________________________

72

30

40

50

60

70

So

un

d P

ressu

re (

dB

A)

Time (24h:00)

Friday LAeq Monday LAeq Tuesday LAeq Wednesday LAeq Thursday LAeq

Figure 6.39 LAeq,1hr levels measured over five consecutive days at nurse station 1

Given that a single 24 hour period did not appear to be representative, a five day measurement period

was then considered (weekdays only due to low occupancy during weekends). Data was available for

two consecutive five day intervals at both nurse station 1 and 4-bed bay A.

Figure 6.40 shows arithmetically averaged LAeq,1hr values from Monday to Friday, for two consecutive

weeks at nurse station 1. It can clearly be seen that the averaged levels are similar in both level and

fluctuation. A χ2 goodness of fit test showed that the two datasets do not differ significantly at the 1%

level. Therefore it may be assumed that a five day measurement period gives reliably representative

data to describe the noise climate at this nurse station.

30

40

50

60

70

So

un

d P

ress

ure

(d

BA

)

Time (24h:00)

Nurse Station 1 Week 1 Nurse Station 1 Week 2

Day time

Night time

Figure 6.40 Average LAeq,1hr levels over 24 hours for week 1 and week 2 at nurse station 1


___________________________________________________________________________________________________________________

73

Data was also available for two consecutive five day intervals for 4-bed bay A. Figure 6.41 shows

averaged LAeq,1hr values from Monday to Friday, over a period of two consecutive weeks in 4-bed bay

A. It can clearly be seen that the averaged levels are similar in both level and fluctuation, again

suggesting that a weekday measurement interval may be representative.

The χ2 goodness of fit test again showed no statistically significant difference between the two

datasets at the 1% level.

20

30

40

50

60

70

So

un

d P

ressu

re (

dB

A)

Time (24h:00)

4-Bed Bay A Week 1 4-Bed Bay A Week 2

Day time

Night time

Figure 6.41 Average LAeq,1hr levels over 24 hours for week 1 and week 2 for 4-bed bay A

It has therefore been shown that, as with the nurse station, a five day measurement period is a

suitably representative interval for 4-bed bay A.

These results suggest that a five day period at a nurse station or in patient accommodation is

sufficiently long to give reliable noise level data.

6.15. Other measured acoustic parameters

6.15.1. Reverberation times

It was decided that it would be possible to make some reverberation time (RT) measurements in the

unoccupied ward accommodation during the weekend, without causing undue disturbance to staff and

patients. Balloon bursts from thick latex 14 cm balloons were chosen as the noise source. As

discussed in Section 5.3.8 the number of source and receiver positions used were in accordance with

the British Standard BS EN ISO 3382-2 (1998) for ‘engineering’ work.

Table 6.4 shows the measured RT20 values (to the nearest 0.05 s) in three rooms, together with room

volume, ceiling area (which is the main area of acoustic absorbency) and the glazing area. This

building was built in line with the previous acoustic design guidance, HTM 2045 (NHS Estates, 1996),


___________________________________________________________________________________________________________________

74

as discussed in Section 6.4. All the measured RT values would be considered to be very low; well

within the recommendations of this guidance.

Table 6.4 Reverberation times measured in different ward accommodation

Room

Description

Volume (m

3)

Ceiling area (m

2)

Glazing area (m

2)

RT20 (s) @ 1kHz

4-bed bay B 168.5 62.4 9.1 0.28

Single room A 57.7 19.5 10.5 0.32

Single room B 40.3 14.9 5.6 0.26

It can be seen that the RT in single room A is slightly longer that the RTs in the other two areas. This

is probably due to the larger area of glazing in room A, as described in Section 6.6.3.

6.15.2. Ambient noise levels

30 second measurements of ambient noise levels were made in two empty single patient rooms and

one empty 4-bed bay during the day time. The results are shown in Table 6.4.

Table 6.5 Ambient noise levels measured in unoccupied patient accommodation

Room description

Ambient noise level (LAeq)

4-Bed Bay B – windows closed

35.0 dB

4-Bed Bay B – windows open

37.5 dB

Single patient room A – windows closed

31.6 dB

Single Patient Room B – windows closed

37.7 dB

Single patient room B – windows open

40.3 dB

Table 6.5 shows a difference of 6.1 dB between the quietest and noisiest rooms with the windows

closed. This is thought to be predominantly due to the amounts of low level air flow through the ceiling

vents. In some rooms the air flow was much more noticeable than in others. The mechanical

ventilation system on this ward is controlled centrally, and not on a room-by-room basis, and so it

would be expected that airflow in all rooms would be constant. However, in discussions with ward


___________________________________________________________________________________________________________________

75

staff, the differences in air flow and also heat levels were mentioned on several occasions. This

suggests the mechanical ventilation system may not be working as designed.

Rooms situated on the west side of the building have windows that can be opened. It can be seen in

Table 6.4 that there is an increase in ambient noise levels of approximately 2.5 dB when a window is

opened. This increase is thought to be mainly caused by traffic noise, as the hospital is situated in

central London.

6.16. Results of the staff questionnaire surveys

The design of the questionnaire surveys was discussed in detail in Section 5.4 and the administration

of the questionnaires in Section 6.9.

In total 12 staff completed the questionnaires. The following sections discuss results from the

questionnaires and show the differences between staff perceptions.

6.16.1. Staff profile

To establish certain attributes about the staff, the first section posed a number of basic questions. Out

of the 12 respondents only 17% were male and 83% were female. The majority of staff were relatively

young, with 75% in the age group 20-30, 17% in the age range 31-40, and 8% in the age range 41-

50. The average length of time that staff had worked on the ward was just over 2 years, but the length

of time working at Great Ormond Street Hospital was longer for some staff, suggesting internal

transfer from other wards.

6.16.2. Noise annoyance and interference

General feelings of noise annoyance were investigated by asking staff to what extent they were

annoyed by noise. It can be seen from Figure 6.41 that 18% of respondents felt moderately annoyed

by noise, with 45% of respondents ‘very much’ annoyed by noise in their work environment. Thus in

total 63% of staff were moderately or greatly annoyed by noise. It is interesting to note that no-one

selected the ‘extremely’ annoyed category. It should be remembered that all 12 permanent members

of staff on the ward completed the questionnaire so it is not the case that responses were received

only from those concerned about noise.


___________________________________________________________________________________________________________________

76

Figure 6.41 Distribution of the extent of staff annoyance

Staff were asked to rate the annoyance of various noise sources on a scale of 0 to 4, with 0 indicating

‘not at all annoying’ and 4 indicating ‘a great deal’. Figure 6.42 shows the percentages of staff who

rated a noise event with a 2, 3 or 4, and as such could be said to be more than a little annoyed by the

event.

0 10 20 30 40 50 60 70 80 90 100

External noise

Doors banging

Internal telephone

Staff talking on the telephone

General conversation

Nurse call

Doorbell

Footsteps

Medical Equipment

Cleaning

Rubbish bins

Trolleys

Meal times

TV / radio

Mobile phones ringing

Talking on mobile phones

Visiting time

% of staff rating annoyance event 2 or above

Figure 6.42 Percentage of staff rating an annoyance noise event with a 2, 3 or 4

Figure 6.42 clearly shows that the four most annoying sources of noise to staff are the ward doorbell,

nurse call, internal telephone and medical equipment alarms, which were all rated by over 80% of

staff as annoying. This response is consistent with the views of the ward manager with regards to


___________________________________________________________________________________________________________________

77

these systems. Visiting time and talking on mobile phones are found to be the next most annoying

sources of noise, rated by over 60% of staff.

Respondents were asked to what extent noise interfered with their ability to work effectively. Figure

6.43 shows that 42% felt noise ‘moderately’ interfered with their ability to work; with only 8% feeling

that noise interfered ‘very much’. It appears from these responses that noise interference is perceived

to be less of an issue than noise annoyance.

Figure 6.43 Distribution of the extent of noise interference with work

Staff were also asked to rate how much each noise event interfered with their ability to carry out their

job effectively (again the rating scale of 0 to 4 was used). Figure 6.44 shows the percentage of staff

who rated a noise event with a 2, 3 or 4, and as such it could be said that this noise event interfered

to some extent with their ability to carry out their job effectively.

Figure 6.44 shows clearly that as with noise annoyance, the four sources of noise which were felt to

cause the most interference were the nurse call and internal telephone (both rated by over 80% of

respondents), and the ward doorbell and medical equipment alarms, (both rated by over 70% of

respondents). Talking on mobile phones is ranked fifth, as with noise annoyance, with 50% of

respondents finding this activity interferes with their ability to carry out their job effectively.


___________________________________________________________________________________________________________________

78

0 10 20 30 40 50 60 70 80 90 100

External noise

Doors banging

Internal telephone



Nurse call

Doorbell

Footsteps

Medical Equipment

Cleaning

Rubbish bins

Trolleys

Meal times

TV / radio



Visiting time

% of staff rating interference event 2 or above

Figure 6.44 Percentage of staff rating an interference noise event with a 2, 3 or 4

The corresponding LAmax values for the doorbell, nurse call and internal telephone are indicated on the

figure. It can be seen that all the values for the doorbell and nurse call are higher than would be

expected in a ward environment, which is again consistent with the views of the ward manager.

6.16.3. Important sounds

To aid understanding of which sounds were felt by staff to be important to be heard in order to carry

out their jobs effectively, staff were asked to rate different noise events on a scale of 0 to 4, where 0

indicated ‘not at all important’ and 4 indicated ‘extremely important’.

It can be seen in Figure 6.45 that ‘medical equipment alarms’ are considered by staff to be the most

important noise events with a mean value of nearly 3.5 out of the maximum 4, followed by the ‘nurse

call’ and ‘patients calling out’ with means of around 3.0. Given the annoyance / interference felt by the

staff with regards to the nurse call, perhaps a different type of alert is more suitable, perhaps making

use of silent technologies such as a personal handset which vibrates. Given the necessity for staff to

be aware of the nurse call, careful consideration must be given to ensure that a suitable system is

found that is not so subtle that it could be missed by staff.

77.9 dB LAmax

80.6 dB LAmax

72.3 dB LAmax


___________________________________________________________________________________________________________________

79

Figure 6.45 Mean importance rating of certain noise events

6.17. Patient questionnaires

In total 31 parents / patients completed the questionnaires. The following sections discuss results

from questionnaires and examine the parent / patient perceptions of the noise environment.

6.17.1. Parent / patient profile

Out of the completed questionnaires, 55% were filled out by parents alone and 45% by the parent

with input from their child. Of those questioned, 10% of the parents were male and 90% were female,

with 39% male patients and 61% female. Figures 6.46 and 6.47 show the distribution of ages of both

parents and patients. It can be seen in Figure 6.46 that the majority of parents were aged between 31

and 50 years, with Figure 6.47 showing a fairly even split in relation to the patients’ age, apart from

children under five years old.

0

10

20

30

40

50

20-30 31-40 41-50 51-60 60+

% o

f re

po

nd

en

ts

Age range (years)

0

10

20

30

40

< 5 5-10 11-13 14-18

% o

f re

po

nd

en

ts

Age range (years)

Figure 6.46 Parents by age bracket Figure 6.47 Patients by age bracket

Out of those questioned, 87% were staying in a 4-bed bay, with an average length of stay of four

days.


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6.17.2. Noise annoyance

The next section of the questionnaire considered day time noise annoyance and night time

disturbance. The questionnaire sought to identify the sources of noise that may annoy or disturb

patients. Respondents were given two lists of noises and were asked to rate the day time annoyance

and night time disturbance on a scale of 0 to 4 (where 0 indicated no annoyance / disturbance and 4

indicated a great deal). Several lines were left blank at the bottom of the lists for patients to add and

rate additional noise sources.

Parents / patients were first asked how they perceived the day time noise environment on the ward.

Figure 6.48 shows that the highest number of those questioned, 58%, felt that the ward was ‘a little

noisy’ during the day, 32% felt that the ward was quiet or very quiet, while 10% felt it was very noisy.

It may be interesting to note that no-one selected the ‘extremely noisy’ category.

Figure 6.48 Distribution of the extent of parent / patient annoyance during the day time

Although there was a high percentage of people that considered the ward to be a ‘little noisy’ only

23% of respondents were actually annoyed by noise during the daytime.

The patients who had indicated that they were annoyed by noise during the day, were then asked to

rate the annoyance of various noise sources on a scale of 0 to 4, with 0 indicating ‘not at all annoying’

and 4 indicating ‘a great deal’. Figure 6.49 shows the percentage of patients who rated a noise event

with a 2, 3 or 4, and as such could be said to be more than a little annoyed by the event. As can be

seen clearly the percentages of those annoyed by any events were very low, with the largest

percentage of respondents (25%) annoyed by medical equipment alarms, followed by noise from TV

and radio use rated by 19%, and mobile phones ringing rated as annoying by 16% of respondents.

Day time annoyance Day time annoyance


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0 10 20 30 40 50 60 70 80 90 100

External noise

Doors banging

Internal telephone



Nurse call

Doorbell

Footsteps

Medical Equipment

Cleaning

Rubbish bins

Trolleys

Meal times

TV / radio



Visiting time

% of parents / patients rating annoyance event 2 or above

Figure 6.49 Percentage of parents / patients rating an annoyance noise event with a 2, 3 or 4

Patients were next asked how they perceived the night time noise environment on the ward. Figure

6.50 details the responses, showing that during the night 45% of those questioned felt that the ward

was either ‘very quiet’ or ‘quiet’. The highest percentage, 42%, found the ward to be ‘a little noisy’ and

13% felt that the ward was ‘very’ or ‘extremely noisy’.

Figure 6.50 Distribution of the extent of parent / patient disturbance during the night time

Night time disturbance


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When questioned whether they were actually disturbed by noise at night, 70% of respondents said

they were disturbed.

Patients who had indicated that they were disturbed by noise during the night were asked to rate the

annoyance of various noise sources on a scale of 0 to 4, with 0 indicating ‘not at all annoying’ and 4

indicating ‘a great deal’. Figure 6.51 shows the percentage of patients who rated a noise event with a

2, 3 or 4, and as such could be said to be more than a little disturbed by the event.

0 10 20 30 40 50 60 70 80 90 100

External noise

Doors banging

Internal telephone



Nurse call

Doorbell

Footsteps

Medical Equipment

Rubbish bins

Trolleys

TV / radio



Other patients cying out

% of parents / patients rating disturbance event 2 or above

Figure 6.51 Percentage of parents / patients rating a disturbance noise event with a 2, 3 or 4

As with day time annoyance, medical equipment alarms were again rated as the most disturbing

noise source, in this case, by over 50% of respondents. The second most disturbing noise source was

banging doors (35%), followed by TV and radio usage (29%).

6.17.3. Positive sounds

Looking at sound in a positive rather than in a negative light, parents / patients were asked if there

were any sounds that they found comforting. 94% of answers were left blank with only two completed

responses: ‘the footsteps of nurse coming to reset instruments’; and ‘people talking / relatives visiting’.

Respondents were asked if they felt that there was ever too little sound in a room. Only 7% of those

completing the question felt there was, but surprisingly these respondents were in 4-bed bays.


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6.17.4. Privacy and ease of hearing

Parents / patients were asked whether high background noise might make it difficult to hear doctors

and nurses who talk to them. The majority of respondents, 81%, said they could ‘always clearly hear

what people say’, with only 19% feeling that ‘occasionally high levels of noise can make it hard to

hear’. Interestingly one of these respondents was staying in a single room. No respondent reported

any hearing impairment.

Conversational privacy was investigated by asking whether the parent / patient felt that they could

have a private conversation at their bedside. 29% said that they did not feel they could speak

privately, all of whom were in 4-bed bays. Out of those who said they felt they could speak privately,

38% of people said they would use their normal voice, with 62% feeling that they would need to lower

their voice.

6.17.5. Patient’s questionnaire comments

Parents / patients were invited to make additional comments at the end of the questionnaire if they

wished. Many of the comments made were in relation to the use of radios and TVs without

headphones. A detailed list of these comments is shown in Appendix B.

6.18. Summary of results

This section summarises the main findings from the pilot study:

� Measurements made at the nurse stations and 4-bed bays were found to be consistent, with

day time levels at the nurse stations around 58 dB LAeq and levels in the 4-bed bays around

52 dB LAeq.

� Levels measured in the single patient rooms averaged around 50 dB LAeq, but were much

less consistent. The differences in measured levels were affected in part by the amount of

care required by the patient, and by the behaviour of the individuals in the room. For example,

the use of television at high volume and mobile phone conversations both contributed to

higher levels.

� It was more difficult to build up a complete picture of high level noise events in the multi-bed

accommodation. In the single rooms it was possible to identify some patterns as there was

generally one patient and parent present, but in the 4-bed bays it was thought that more

localised sounds were creating the trigger files.

� Night time levels were in general found to be 10 dB lower than day time levels.

� Reverberation times measured in patient accommodation were very low, due in part to the

good acoustic properties of the ceiling tiles used. However, the use of solid plaster ceilings in

hallways and at the nurse stations may lead to longer reverberation times and higher noise

levels in these areas.


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� Ventilation noise was on occasions noticeably loud, and was not controlled on a room-by-

room basis.

� 63% of staff questioned were ‘moderately’ or ‘very much annoyed by noise in their work

environment, and 50% felt noise ‘moderately’ or ‘very much’ interfered with their ability to

work.

� Staff questionnaire responses consistently found that the internal telephone, nurse call, ward

doorbell and medical equipment alarms caused the most annoyance and interference. This

suggests that a level of noise control should potentially be applied to these systems, or

alternatives sought.

� 70% of parents / patients were disturbed by noise at night, but only 23% annoyed by noise

during the day.

� Medical equipment alarms, banging doors and the use of television and radio were rated as

the most disturbing sources of noise to patients / parents at night. Soft door closers and the

use of headphones for television and radio usage would be a simple and relatively cheap

solution to reduce some of this annoyance. The use of medical equipment alarms could be

studied further. Some alarms may be un-necessary or are set too loud; however, a careful

balance must be sought as these alarms are rated as the most important noise sources for

staff to hear.

� Lower percentages of parents / patients rated noise annoyance and disturbance events than

the staff. This may be partly due to their not wanting to be critical as their child is unwell and

they are grateful to the staff and hospital, or because they are focussed on their child’s care

and wellbeing and noise is less noticeable than it may be in other situations.

The pilot study aimed to provide useful feedback for the redevelopment team and the ward manager

on the site. Following its completion, a full report was provided for each team member involved, and

the ward manager of Sky Ward was also informed of the relevant findings. Follow up meetings were

held with ward staff, which are discussed in the following section, and further highlighted areas that

could potentially be improved with regards to noise control.

6.19. Follow up discussions

Several meetings were held with the staff of Sky Ward to present the pilot study findings and discuss

changes that could potentially lead to an improvement in certain areas. Members of the

redevelopment team also attended the meetings. A summary of the discussions are shown below.

Television usage on the wards

Many of the patient comments indicated that one of the main issues was around the use of television /

radio without the use of headphones. Further discussion with staff regarding this issue yielded some

interesting findings and attitudes towards the use of televisions on the ward:


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� There are four flat screen TVs in each of the 4-bed bays, all suspended from the ceiling at the

end of each patient’s bed. A remote control is supplied with each TV, but it appears that all

remote controls are identical, so they control not only the patient’s TV but all four installed in

the bay. The consequence of changing a channel or adjusting the volume on one television

could be that the other televisions in the bay are affected. Staff also mentioned that the

default volume when the televisions are switched on is set very loud.

� The type of television installed on the ward requires ‘wired’ headphones, which is a difficult

option as they are positioned so far from the bed head. There are some portable DVD players

currently available which could be watched with headphones.

� Staff felt that many of the patients with special needs would not be able to wear headphones

and they appeared slightly reluctant to enforce the general use of headphones. It was felt that

some patients would be used to having the TV on all the time at home and it would not be fair

to prevent the patient from behaving in the same way on the ward; even to the extent of falling

asleep to the noise from the TV.

� Younger members of staff did not appear to consider extensive and loud use of TVs as

unacceptable and did not seem to be aware that that one patient’s behaviour might negatively

impact the others on the bay.

Banging doors

Banging doors were listed as a disturbance in the patient questionnaires. Staff mentioned that the

quiet closers on most doors did not seem to work effectively, resulting in a loud thud as the door

closed. This had recently become such a problem that staff have draped towels over doors to stop

them banging (although this has since been stopped by the ward manager).

The door of the dirty utility room was mentioned as being particularly loud and prompted further

discussion on the difficulty of entering the dirty utility room whilst carrying spillable objects. It was felt

that a kick bar on the base of the door might be more effective than an ordinary handle. The necessity

for security for the utility room was also discussed with staff feeling that the use of a swipe card or key

code system could potentially lead to even greater access problems. Many staff felt that it was

unnecessary to have security for this room at all. Single patient room 11, the staff room and kitchen

were all cited as having particularly loud doors.

The doorbell

The ward doorbell had been noted by the ward manager as being extremely loud and was shown to

be a source of interference and annoyance for staff. As a consequence, a new system had been

installed with a volume control. Although the ward manager had turned down this volume, no

difference had been perceived by the staff, who still felt it was extremely loud, especially at night.

The use of the doorbell was discussed further. Many of those ringing out of hours tended to be visiting

or staying with their children on the ward and seem to ignore the sign asking for the bell to be rung


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86

once. It was also mentioned that if someone leaves their finger on the buzzer for a long period, it

continues to ring. This annoys the staff immensely, especially late at night when fewer staff are

present on the ward and may be busy with other duties. Staff felt that it would be useful if the doorbell

could somehow be limited to ring once every 30 seconds.

The possibility of issuing passes was investigated. However, this has been trialled previously and

many passes were never returned to the ward. With each pass costing between £5 and £10 this

option was considered too expensive to be workable.

It was also mentioned that the security camera pointed at the ward entrance, which is installed so that

staff can identify those ringing the doorbell, is pointed at the back of the heads of those ringing. The

camera’s validity in terms of security was felt to be questionable.

Nurse Call

This was another system that was identified as being extremely loud, with no perceptible volume

change between the day and night time setting. This was still considered to be problem by the ward

staff.

Miscellaneous Alarms

The Controlled Drugs cupboard has both a light and an alarm. This alarm is found to be very

annoying by the staff.

Internal Telephones

Internal phones at the nurse stations were also shown to be an annoyance and to interfere with staff

duties. Staff felt that the phones ring a great deal and are loud. According to the members of staff

present, they can be turned down with the exception of the emergency phone, which is a fixed volume

(very loud). Various ideas for replacements were discussed, including bleepers and portable phones.

If the ward clerk is away from her desk, the main ward phone diverts onto the ward and consequently

the ward staff have to deal with the calls and pass messages back. The possibility of installing a voice

mail system for the ward clerk was discussed and considered to be a positive idea by the staff. This is

an illustration of a simple, cost effective solution that can be found by directed discussion.

Doctor’s office alarm

As discussed, Sky Ward is mechanically ventilated and the system is controlled centrally. Staff

mentioned that certain rooms are particularly warm and some particularly cold, especially if the beds

are situated directly under the ceiling vents. One room that is always very warm is the doctor’s office,

which leads to the door being constantly propped open. With the door open a very high pitched alarm

is activated, which is continually reset. This is extremely annoying to staff.


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6.20. Conclusions

The main purpose of the pilot study was to trial the proposed methodologies to ensure that meaningful

results could be obtained in line with the research proposal. Both the objective measurements and the

subjective questionnaire surveys were generally felt to be successful, with a number of specific

aspects discussed in further detail below.

� The pilot study showed that suitable microphone positions could be found, which would allow

for meaningful comparisons. However a degree of flexibility was required so as to minimise

the impact of the microphone and associated equipment on staff duties and patient care.

� Trigger files were successfully used to identify sources of high level noise, but analysis was

found to be extremely time consuming. It was felt that further consideration was needed to

ascertain the best way to present this data in the main study.

� A working week was shown to be a representative measurement interval. This interval was to

be further validated during the main study if possible.

� Both staff and patient questionnaires generally worked well, with only two questions requiring

a small amount of re-wording to ensure complete clarity.

Both the study findings and results of the follow up meetings are currently being used to positively

influence / inform the choice of systems and ward design for the next phase of the Great Ormond

redevelopment. Improvement to some of the existing systems on Sky Ward is also being investigated,

and it is hoped that some noise control measures can be taken.

The following chapters describe the main study which involved noise and questionnaire surveys in a

medical and surgical ward at Bedford Hospital and in three wards at Addenbrooke’s Hospital,

Cambridge. As part of the Bedford Hospital study, a ceiling intervention study was also carried out

and changes to sound levels and reverberation times were investigated. This is discussed in further

detail in Chapter 8.

Acoustic Design for Inpatient Facilities in Hospitals Bedford Hospital

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7. Bedford Hospital

7.1. Introduction

Two wards at Bedford Hospital were the subject of the main study, which took place over an eight

month period, from April to November 2010. Working in collaboration with the Estates team, two

inpatient wards of similar layout were chosen in the main five storey ward block. For comparison

purposes one ward was a surgical ward, the other medical. Within the study time frame a

refurbishment of the medical ward was also planned. This was of particular interest to the Estates

team, who wanted to establish the effects of changing reflective ceiling tiles for those with good

acoustic properties. The results of this change are discussed in further detail in Chapter 8.

This chapter begins by looking at the background of Bedford Hospital, providing an overview of the

acoustic design considerations of the ward block and exploring the hospital policies and equipment

usage that may affect the noise levels in the study wards. The chapter continues by examining the

two wards participating in the study individually, including their design layouts and the daily routines.

Objective results from each ward are reported, and staff and patient perceptions of the noise

environment are explored.

7.2. Background

Bedford Hospital opened in 1803, consisting of just six beds, and employing a staff of four clinicians.

Now, over two centuries later, the hospital provides 403 patient beds and has a staff of over 2000.

Services are provided for around 270,000 people in mid and north Bedfordshire and include medical,

surgical, paediatric and neonatal wards; A&E; an Acute Assessment Unit (AAU); and a specialist

cancer centre. One of the original buildings still exists, as can be seen in Figure 7.1, but there have

been many additions, many of which were built in the 1970’s and 1980’s (as seen in Figures 7.2 and

7.3). The hospital continues to expand.

Figure 7.1 Original building, Bedford Hospital (1803)


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Figure 7.2 Five storey ward block Figure 7.3 Main hospital entrance

7.3. Building acoustic design considerations

The main five storey ward block was constructed in the early 1980’s under ‘Crown Immunity’, which in

effect means that this building was exempt from building regulations. It is unknown if any acoustic

guidelines were taken into consideration during the build.

The construction of the ward block is primarily concrete, naturally ventilated and single glazed. The

two inpatient wards chosen to participate in the study are of identical layout, and situated a floor apart.

Each ward is designed around a central corridor which runs down the length of the ward. The main

patient accommodation is situated to one side of this corridor and consists of a number of open four

and six bed bays. These bays look out over the main hospital entrance, car park and several

connecting roads, one of which is a busy main road; although traffic flow is relatively slow due to

traffic lights. On the opposite side of this main corridor are the staff healthcare utilities, offices,

storerooms, a kitchen and four single patient rooms, which overlook the new maternity wing. Ward

plans are shown in Sections 7.5 and 7.6.

Both study wards have suspended ceiling grids with perforated acoustic ceiling tiles in the majority of

the multi bed bays, single rooms, offices and corridors; although there are exceptions, further details

of which are discussed in Section 7.6.2. Other acoustic absorbency is provided by the fabric privacy

curtains, which can be pulled fully around each bed; upholstered easy chairs where patients can sit

when out of bed; window curtaining; mattresses and bedding. All patient accommodation has heavy

duty vinyl flooring and solid plastered walls.

7.4. Hospital policies and equipment common to both wards

Before looking at the two study wards individually, the hospital policies and equipment that are

common to both wards and may have an effect on noise levels, are examined.

7.4.1. Meal times

‘Protected meal times’ are in use throughout the hospital. This means that during breakfast, lunch and

evening meal times clinical visits cease and visitors are asked to leave the ward (except family


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members if they are providing assistance with eating). This is primarily to allow the hospital staff to

monitor what is being eaten and to provide a more relaxing environment for the patients.

Each ward has a kitchen which is used for plating up hot meals and for washing up plates and cutlery

(shown in Figure 7.4). There are also fridges and a food warmer. The kitchen may be a source of

noise for patients in the opposite bay, as the kitchen door is always left open. Meals and drinks are

served to patients from a trolley, another potential source of noise.

Figure 7.4 Medical ward kitchen

Meal times are as follows:

� Breakfast is served from 08.00 to 08.30 and is followed by a tea round. Breakfast is

usually cold except for porridge

� Mid morning tea is served from 10.00 to 10.30

� Lunch is from 12.30 to 13.15, with tea served at around 13.00. Lunch is usually a hot

meal which is brought up to the ward kitchen in a heated trolley. Meals are then plated

up before being served to patients one bay at a time on a smaller trolley.

� Afternoon tea is served at 14.30

� Tea (supper) is generally a selection of sandwiches and is served from 17.30 to 18.15,

followed by a tea round at 18.00

� Drinks are available in the evening from 20.00 to 21.00

7.4.2. Ward design

At the entrance to each ward there is a ward clerk’s desk which acts as a reception area. Behind this

is a staff room and kitchen, both of which can be noisy areas. However, the bay directly opposite the

ward clerk’s desk is the only bay likely to be adversely affected by noise.

The nurse station is situated halfway down the main corridor. Potential high level noise sources here

are the nurse call, internal telephone, staff conversation and the carrying out of administrative tasks

which may affect the nearby bays and single rooms.


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7.4.3. Occupancy levels

Unlike the pilot study hospital, both these wards have a high occupancy rate throughout the entire

week, including weekends. It was therefore considered valid that noise level measurements should be

made at each location over a full seven day period, rather than the five day interval used during the

pilot study.

7.4.4. Shift patterns

Staff day shifts start at 07.00 and end at 19.30, with night shifts starting at 19.00 and ending at 07.30.

There is a half hour overlap at the beginning and end of the shifts. During this overlap there is usually

a handover session in the staff room (opposite 4-bed bay 1). Higher levels of noise may be attributed

to these changeover periods.

7.4.5. Visiting hours

These are officially 14.00 to 20.00. Attitudes amongst ward sisters vary regarding the enforcement of

these hours. Some staff consider that the positive effect on patients of visitors outweighs the other

negative aspects of having numbers of visitors on the ward out of official visiting hours.

7.4.6. Ward access

There is no ward security to prevent anyone walking on to the ward. This removes the need for a

doorbell, which could potentially be a source of noise annoyance.

7.4.7. Access to patient accommodation

All multi bed bays on the wards are open to the corridor; there are no doors. The doors of the single

patient rooms are generally left open during the day for observation purposes, but are closed at night

and during visiting times, where there is someone on hand to call a nurse if required.

7.4.8. Cleaning staff

In-house cleaning staff are used throughout the hospital rather than contractors. It is felt that this

enables more control of cleaning regimes and promotes better work ethics and loyalty. Each ward has

a dedicated cleaner who works from 07.00 until 15.00. Duties include mopping, sweeping and floor

buffing.

7.4.9. Mobile phone policy

The hospital policy specifies that mobile phones should only be used in the lobby areas and not on

the wards. This is partly to avoid disturbance and partly because mobile phones have camera and

recording capabilities which could potentially cause a breach of patient privacy or confidentiality


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7.4.10. Entertainment systems

A HTS Hospicom system is provided at each patient’s bedside. This is a pre-pay TV / radio /

telephone console. Patients are issued with headphones. A photograph of the console is shown in

Figure 7.5.

7.4.11. Rubbish bins

Quiet closing foot operated rubbish bins are in use throughout the wards. However, the opening

mechanisms are found to be quite noisy especially if the bins are placed too close to a wall or nearby

object, which then tends to be hit by the lid with some force. The body of the bins are also metal and

undamped; if a heavy object is dropped inside, this can also be a source of noise.

7.4.12. Staff call

The emergency staff call system is activated by the patient pushing a button at their bedside. This

causes a red light to flash on the ceiling outside the bay and sounds an intermittent alarm at the nurse

station. This will continue until cancelled by a member of staff.

7.4.13. Medical equipment alarms

Alarms generally sound if fluids are low or as a warning that a piece of equipment, for example a

canular, has fallen out. Mattresses used on the wards bleep if they become under-inflated.

7.4.14. Trolleys

Meals, drinks rounds, medication and dressings are all taken to the patient’s bedside on trolleys. Beds

themselves are on wheels, as is the majority of medical equipment for ease of movement. Deliveries

of fresh linens, food and other ward supplies all arrive at the ward in wheeled metal cages or on

trolleys.

7.4.15. Internal telephones

A number of internal telephones can be found on each ward, in the staff office, at the ward clerk’s

desk, the nurse station and on other staff desks in the ward corridor.

7.4.16. Hand gels

Automatic hand gel dispensers have been installed on the ward. These are motorised and work using

a sensor as shown in Figure 7.6.


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Figure 7.5 Hospicom entertainment console Figure 7.6 Automatic hand

gel dispenser

7.5. Medical ward

This ward is located on the fourth floor of the main hospital building and specialises in

Gastroenterology and care of the elderly. Elderly patients admitted to this ward are often confused

and may be suffering from a degree of dementia. Generalised medical care is also provided if the

beds are needed by patients from other specialties, for example Oncology.

Patients range in age from 18 upwards. The majority of patients have come via their GP to the AAU

(either in an ambulance or their own vehicle) and then to the medical ward following their assessment.

Patients on this ward are generally recovering from infections.

The ward has 30 beds in total, with three 6-bed bays, two 4-bed bays and 4 single rooms (an example

of which is shown in Figure 7.7). Patients are predominantly male, with one all female 4-bed bay and

single rooms used for female patients when necessary.

Figure 7.7 Single patient room

The medical ward was the first ward at Bedford Hospital to participate in the study, and before

commencement a number of issues needed to be clarified. An initial meeting was held with the ward

manager and the head of the hospital infection control team, who were shown the sound measuring

equipment. There were no undue concerns regarding the cleaning of the equipment as it would be


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97

located in each position for only one week. It was felt that if it did become contaminated, the

equipment case was such that it could easily be cleaned using an alcohol wipe.

Measurement locations were also discussed and possible microphone positions that would be

acceptable to the staff and patients were identified in the multi-bed bays, single rooms and at the

nurse station. For comparison purposes it was important that the microphone could be placed in

similar locations in each accommodation type, and for this to be repeatable in the surgical ward. A

ward plan showing the microphone positions can be seen in Figure 7.10 on page 99.

To minimise the risk of theft, ward staff felt that it would be sensible to hide the environmental case

containing the sound level meter either in or behind a cupboard. Given the positioning of the ward

furniture and the length of cable available (5 m), this meant that the microphone would need to be

situated close to the edge of a room, often in the corner. Due consideration was given to the possible

increase in sound pressure due to wall reflections or corner reflections. A number of tests were

carried out to investigate this, and the results can be seen in Appendix C. No significant increase in

measured level was found due to the location of the microphone close to a wall or in the corner of the

room.

To avoid the microphone being knocked or contaminated, and to be as unobtrusive as possible, it was

felt that suspending the microphone from the ceiling would be ideal. A 300 mm bracket was designed

which simply clipped around the ‘T’ shaped ceiling grid without disturbing the ceiling tiles. If the ceiling

bracket could not be used, for example in the case of a solid ceiling, the microphone was mounted on

a small tripod which was securely fastened out of reach. Figure 7.8 shows the microphone suspended

from the ceiling grid and Figure 7.9 shows the microphone and tripod positioned on a light above a

mirror in a single room.

Figure 7.8 Microphone suspended from ceiling Figure 7.9 Microphone on tripod

Questionnaires were reviewed by the ward manager and it was decided that they would be distributed

by the ward clerk to those patients who had been on the ward for over 24 hours and were felt to be fit

enough to complete the survey. Staff questionnaires were to be left for staff to complete in the staff

room.


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98

As with the pilot study a number of laminated advertising posters were displayed throughout the ward

common areas. These posters were aimed at both staff and patients and explained in simple terms

why and how the study was being undertaken. In addition to these posters the ward manager

personally discussed the study with all her staff during staff meetings.

7.5.1. Ward specific information

Staffing levels

The nursing staff levels are highest during the morning with seven dedicated nursing staff. This drops

to five during the afternoon and four at night. Other dedicated ward staff include a housekeeper; three

domestics; a ward clerk; an occupational therapist; and a physiotherapist.

Ward routines

The first patient visits by clinicians for general observations and the administration of intravenous

antibiotics begin at 06.00. However, activity on the ward does not begin fully until 07.30, when the

main lights are switched on.

Two ward rounds begin at 09.00 (Monday and Friday), with two consultants from different specialities:

‘Care of the Elderly’ and ‘Gastroenterology’. As well as the consultant ward rounds, the junior doctors

work in the ward throughout the day talking to patients, checking bloods and organising discharges. In

addition to the doctors ward rounds, bloods are also taken by the phlebotomists at 09.00-09.30 and

18.00-19.00.

The ward lights are dimmed after 21.00.

Sources of noise specific to the medical ward

Patients who are suffering from dementia are given a wrist tag which causes an alarm to sound if the

patient tries to leave the ward.

There is a pneumatic system for the distribution of pharmaceuticals close to the nurse station and a 6-

bed bay.

Figure 7.10 Detailed plan of the medical ward showing microphone positions

Pneumatic system

Microphone position

Sink


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100

7.6. Medical ward overall noise survey results

Noise level measurements were made at eight different locations on the medical ward. Table 7.1

shows the locations, measurement periods and the patient genders where applicable.

Table 7.1 Medical ward - measurement locations, time periods and patient gender

Position Length of measurement period Patient gender

Ward entrance 7 days N/A

Nurse station 7 days N/A

4-bed bay 1 12 days Male




Single room A 5.5 days M/F

Single room B 7 days M/F

The results reported for bay 1 are those made after the ceiling tiles were changed for those with better

acoustic properties, as discussed in Chapter 8. This ensured that reported results were comparable

with the other bays on the ward with similar ceiling tiles.

Overall measurements of A-weighted equivalent sound pressure levels (LAeq) for 24 hours, night and

day time were recorded at each location and are shown in Table 7.2.


Position in ward Average of A-weighted equivalent sound pressure levels



Ward entrance 53.7 55.2 46.4

Nurse station 54.0 54.9 50.0

4-bed bay 1 49.4 51.3 41.8

4-bed bay 2 49.8 51.1 44.1

6-bed bay 3 54.0 55.2 50.1

6-bed bay 4 49.7 51.2 42.4

Single room A 59.3 60.6 51.1

Single room B 52.6 53.9 47.3

A summary of the day and night time average levels presented in Table 7.2 are shown graphically in

Figure 7.11 for clarity. As with the pilot study ward, all levels in patient accommodation exceed those

suggested in the WHO guidelines without exception. It can be seen that day time levels measured at

the ward entrance and the nurse station are similar, as are the day time levels in bays 1, 2 and 4.

However, levels in bay 3 and the single rooms are less consistent. The drop between day and night


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101

time levels varies from 9.5 dB in bay 1, to only 5 dB in bay 3 and at the nurse station. Possible

reasons for these differences are discussed in Section 7.6.4.

0

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Ward entrance Nurse station 4-bed bay 1 4-bed bay 2 6-bed bay 3 6-bed bay 4 Single room A Single room B

Sou

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dB

LA

eq

,1h

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Day time LAeq, 16hr

Night time LAeq, 8hr


The following sections examine the noise levels recorded at different locations on the ward in further

detail.

7.6.1. Nurse station and ward entrance

Figure 7.12, shows the average measured LAeq,1hr and LA90,1hr levels over 24 hours for the nurse station

and the ward entrance by the ward clerk’s desk. It can be seen that noise levels in both locations

increase steadily from around 04.30am, and at the nurse station, levels do not decrease substantially

until around 01.00. The levels at the ward entrance decrease earlier than at the nurse station and

remain consistently lower during the night. This is as one would expect given the nurse station is

staffed 24 hours a day, whereas the ward clerk is only at the desk during day time office hours, and

then the desk is only used periodically by other staff. However noise levels at the ward entrance are

also affected by activity in the staff room and kitchen which are situated directly behind the ward

clerk’s desk area, as can be seen in the ward plan shown in Figure 7.10 on page 99.

The measured LA90,1hr levels provide a good indication of the variation in background noise levels over

time. Night time background levels reduce from around 38 dB LA90 to around 34 dB LA90 during the

quietest period, while day time background levels are fairly steady at around 42 dB LA90. Background

levels at the ward entrance exceed those at the nurse station twice during the day: first around the


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time of the morning shift handover, breakfast and start of the morning ward rounds; and secondly

during lunch time, when hot meals are plated up in the kitchen.

20

30

40

50

60

70S

ou

nd

Pre

ssu

re (

dB

A)

Time (24h:00)

Nurse Station LAeq Ward entrance LAeq Nurse Station LA90 Ward entrance LA90

Night time

Day time

Figure 7.12 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station and ward entrance

Viewing averaged noise levels over time, as in Figure 7.12 above, provides valuable information with

regards to level consistency and overall day and night time variation patterns, but does not illustrate

the fluctuating nature of noise in the short term. Figure 7.13 shows noise levels captured at the nurse

station over a ten minute time interval with the microphone approximately 2 m away from the main

desk area. Using the trigger files captured when LAmax exceeds 70 dB, certain high level noise events

have been identified.

Figure 7.13 LAmax,2s and LAeq,2s fluctuating over a ten minute interval at the nurse station

FURNITURE

SCRAPING

ON FLOOR

INTERMITENT

NURSE CALL LAmax,2s

LAeq,2s

CLOSING

ROOM DOORS


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103

The events shown in Figure 7.13 are a good representation of the types of high level noise events

recorded at the nurse station. Furniture scraping is found to be a constant source of high level noise

which could be simply and cheaply controlled by fitting rubber feet or wheels to the chairs used. Doors

are also a problem, with doors to two single rooms situated at the back of the nurse station and a set

of large metal storage cupboards to one side. These often cause high levels of noise on closing.

Again this could be easily and cheaply rectified.

To further illustrate the types and noise levels of typical high level events at the nurse station,

examples are presented in Table 7.3. It should be noted that the levels shown are for individual

events and may not be representative of every noise event of that type.

Table 7.3 Examples of noise events at the nurse station

Noise event LAmax (dB)

Nurse call 72.8

Door banging 77.3

Furniture scraping on floor 85.6

Metal cupboard door 84.3

Internal phone 71.6

Rubbish bin 78.7

7.6.2. Multi-bed bays

Figure 7.14 shows the averaged LAeq,1hr levels measured over 24 hours for two six bed and two four

bed bays. It can be clearly seen that levels for bays 1, 2 and 4 are very similar and follow the same

general pattern of fluctuation. This suggests firstly that an increase in ward size from four to six

patients does not necessarily affect the noise levels, and secondly that the daily ward routines which

contribute to the noise levels are comparable. The levels in bay 3, however, are consistently higher

than those in the other bays, by 4 dB LAeq on average during the day and by up to 8 dB LAeq during the

night. This particular bay is opposite the nurse station, and for observation purposes the patients with

the most serious conditions are placed here. Due to the type of patients on this ward, the main impact

on the noise levels is both from the patients themselves, for example, crying out, coughing and

groaning and the increased clinical activity in the bay. Unlike bays 1, 2 and 4, bay 3 has a solid

plaster ceiling rather than a suspended ceiling with acoustic tiles. This may also have a negative

impact on noise level.

Figure 7.14 also shows that the WHO day / night division is not a particularly good fit. Noise levels

increase steadily from around 05.30 rather than 07.00, and begin to decrease after the evening meal

is served and then further decrease at 23.00. This suggests it might be appropriate to redefine the

‘day’ and ‘night’ time periods for hospital noise assessment.


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104

20

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50

60

70

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d P

ressu

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LA

eq

,1h

r)

Time (24h:00)

Medical 4-Bed Bay 1 Medical 4-Bed Bay 2 Medical 6-Bed Bay 3 Medical 6-Bed Bay 4

Night time Day time

WHO GUIDELINES

Figure 7.14 Average LAeq,1hr levels over 24 hours for the multi-bed bays

Background levels, in terms of LA90, are shown in Figure 7.15. Levels in bays 1, 2 and 4 have been

averaged for purposes of clarity and it can be seen that background levels in these bays are around

39 dB LA90 during the day and 32 dB LA90 at night. Bay 3 has considerably higher background levels of

around 46 dB LA90 during the day and 41 dB LA90 at night, higher than those at the nurse station

opposite (see Figure 7.12).

20

30

40

50

60

70

So

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d P

ressu

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LA

eq

,1h

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Mean LA90 Bays 1,2,4 Mean LA90 Bay 3

Night time Day time

Figure 7.15 Average LA90,1hr levels over 24 hours for the multi-bed bays


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105


Figure 7.16 shows the average LAeq,1hr levels over 24 hours in the two single rooms measured. The

levels measured in the multi-bed bays have been averaged, and the average is also shown on the

graph to allow for comparison between single rooms and multi-bed bays.

It can be seen that levels for single room B are similar to those of the multi-bed bays, but noise levels

measured in single room A are considerably higher. Much of this high level noise was caused by visits

to the patient by groups of relations who would arrive around 14.00 and often stay until 21.00. During

this time conversation was constant. Noise levels were also impacted by the patient’s condition and a

lack of cooperation with members of the nursing staff. Consideration should also be given to the fact

that room A has a solid plaster ceiling rather than a suspended ceiling with acoustic tiles. This may

also have had a negative impact on noise levels.

20

30

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50

60

70

So

un

d P

res

su

re (d

B L

Aeq

,1h

r)

Time (24h:00)

Medical ward - single room A Medical ward - single room B Average of multi bed bays

Night time Day time

WHO GUIDELINES

Figure 7.16 Average LAeq,1hr levels over 24 hours for the single rooms

Figure 7.17 shows the LAmax,2s and LAeq,2s between 14.00 and 17.00 in single room A and illustrates

the impact of visiting time on the noise levels. Average noise levels during this period increase to 66

dB LAeq, with an occurrence of 89.3 dB LAmax.


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106

Figure 7.17 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a three hour period

in single room A

7.6.4. Further analysis of high level noise sources

To help build up a further picture of the sources of high level noise at each location, the numbers of

occurrences of LAmax in 5 dB bands from 70 to 95 dB have been examined. Figures 7.18 and 7.19

show the average number of high level noise events per day and per night in different measurement

locations.

0

50

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200

250

300

350

400

450

500

Nu

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70 ≤ LAmax < 75 dB

75 ≤ LAmax < 80 dB

80 ≤ LAmax < 85dB

85 ≤ LAmax < 90dB

90 ≤ LAmax < 95 dB

Figure 7.18 Average number of high level noise events recorded at each location per day

VISITING TIME


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107

It can be seen that the numbers of high level noise events in single room A during the day exceed

those in all other locations, with on average, over 450 events with LAmax between 70 and 75 dB; over

250 events with LAmax between 75 and 80; and over 100 events with LAmax above 80 dB. As discussed

in the previous section, the majority of these high level events are due to loud conversation during

visiting time, which raises the following question: If this patient had been in a multi-bed bay, would the

visitors have felt more inclined to speak more quietly? The ward manager in this medical ward has a

positive view on the benefits of visiting time, and does not strictly enforce visiting hours. However, are

these long periods of loud conversation actually beneficial to the patient? Would these lengthy visits

have been curtailed if this had been a daily occurrence in a multi-bed bay?

Although, as discussed in Section 7.6.2, overall noise levels in bays 1, 2 and 4 are shown to be

similar, differences can be seen between the bays in terms of the average numbers of high level

noise events. Bay 1 is opposite the ward clerk’s desk, kitchen and staff room and is shown to have on

average over 50 more high level noise events during the day than the next bay along the corridor.

This is thought to be due to noise from the ward clerk’s desk area, kitchen and staff room and this is

further confirmed by patient comments in the questionnaire surveys, as discussed in Section 7.11.

Day and night time average noise levels for bay 3 and the nurse station which is opposite are very

similar, as are the numbers of high level noise events. However, by looking at the overall noise levels

it is unclear whether any of the activities at the nurse station have an adverse effect on noise levels in

the opposite bay or whether they are unrelated. Further investigation appears to suggest that as first

thought; the majority of sources of high level noise in bay 3 appear to be linked to increased clinical

activity and patients’ conditions and behaviour. The nurse call appears to be the only nurse station

related activity which is recorded at comparable levels in bay 3.

Figure 7.19 shows a very different pattern of occurrences of high level noise events during the night. In

this case it is the nurse station and bay 3 which show the highest numbers of events. This is

unsurprising as the nurse station is manned for 24 hours a day, and bay 3 is used for more seriously ill

patients who require constant care. Sources of high level noise at the nurse station are the nurse call,

furniture scraping on the floor, doors banging and administrative tasks, while patients’ crying out and

clinical activity are typical of high level noise events in bay 3.


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108

0

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70

80

90

Nu

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teg

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70 ≤ LAmax < 75 dB

75 ≤ LAmax < 80 dB

80 ≤ LAmax < 85dB

85 ≤ LAmax < 90dB

Figure 7.19 Average number of high level noise events recorded at each location per night

For illustration purposes, typical sources of high level noise recorded in the bays and single rooms are

shown in Table 7.4, together with their noise level (LAmax). It should be noted that the exact position of

the noise source relative to the microphone is unknown. Where human activity is measured it can be

reasonably assumed that this has occurred at the closest bed to the microphone (approximately 2 m in

distance).

Table 7.4 Examples of noise sources and levels on the medical ward


Trolleys (various) 77.7; 84.8

Checking patient's notes at the bedside (ring binder) 83.6

Patient snoring 70.4

Patient's mobile phone ringing 75.4

Cough 79.4

Loud crash (measured in bay 1) 80.9

Medical equipment alarm 72.5

Noisy motorbikes (measured in single room with window open) 72.5

Sirens (unknown if window open or closed) 74.0

Rubbish bin 76.5

Changing bin bag 92.7

Crash from kitchen (measured in bay 1) 94.5

Dropped object in corridor (measured in bay 1) 103.1

Nurse call (measured in bay 3) 72.5

Sneeze 89.4


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109

It can be seen in Table 7.4 that several noise events are measured at over 90 dB LAmax, with a

dropped object generating a level of 103.1 dB LAmax. Such high noise levels would undoubtedly cause

annoyance and disturbance to patients and staff nearby.

7.7. Surgical ward

This ward is located on the 3rd

floor of the main hospital building, directly under the medical ward, and

is for elective orthopaedic procedures. This includes surgery to joints, hands, arms, shoulders and

breast surgery. Patients range in age from 18+ and length of stay ranges from less than 24 hours to

up to around 10 days.

The ward has 26 beds in total, with four 4-bed bays, a 6-bed bay and 4 single rooms. Bays are

predominantly female, with one all male 4-bed bay and single rooms used for male patients when

necessary.

With the equipment already sanctioned by the infection control team, only microphone positions and

questionnaire distribution needed to be discussed with the ward manager, who was extremely

supportive of the study. For comparison purposes it was suggested that similar microphone positions

should be used to those in the medical ward. The ward manager was happy for this to be the case,

and a ward plan indicating these positions can be seen in Figure 7.20 on page 111. As in the medical

ward, the microphone was suspended from the ceiling where possible.

Questionnaires were also reviewed by the ward manager and it was decided that they would be

distributed by the ward clerk to those patients who had been on the ward for over 24 hours and were

felt to be fit enough to complete the survey. Staff questionnaires were to be left for staff to complete in

the staff room.

As in the medical ward a number of laminated advertising posters were displayed throughout the ward

common areas.


Staffing levels

The nursing staff levels are highest during the morning with five dedicated nursing staff. This drops to

four during the afternoon and three at night. Other dedicated ward staff include a housekeeper; three

domestics, ward clerk; dedicated occupational therapist; and a physiotherapist.


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110

Ward routine

Observation rounds begin at 06.00, with drug rounds and first admissions beginning an hour later.

Doctors and anaesthetists arrive for morning admissions around 08.30 and may be on the ward for

several hours. Porters begin to take patients to the operating theatre at this time.

In the late morning, staff begin to take their breaks and patient discharges are discussed, causing

more activity around the nurse station. Physiotherapists & occupational therapists carry out their

duties on the ward; drug rounds continue; porters are busy taking patients for X-rays and bringing

back patients from surgery.

From 13.30 until 14.00 there is a shift handover which takes place both in the office and at the

bedside. Sometimes this can lead to five or six people gathered around a patient’s bed, which can

generate some noise.

The second round of admissions arrive at 14.00; observations of patients back from surgery continue;

bloods and x-rays are taken in preparation for surgery; doctors arrive on the ward to visit new

admissions.

At 16.00 staff begin to take breaks and at 17.30 day surgery patients begin to go home. Drug rounds

are ongoing.

Sources of noise specific to the surgical ward

The following are potential sources of noise on the ward:

� The defibrillator self tests at 03.00

� A series of bleeps from the fire alarms can be heard down the corridor – possibly a self test?

� The fire exit door at the end of the ward is heavy and is ill-fitting in its frame. Although it is

fitted with a quiet closer it vibrates loudly on closing.

� The cupboard, which is opposite 4-bed bay 4, has a noisy metal roller shutter.

Figure 7.20 Detailed plan of the surgical ward showing microphone positions


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112

7.8. Surgical ward overall noise survey results

Noise level measurements were made at six different locations on the surgical ward. Table 7.5 shows

the locations, measurement intervals, and the patient genders where applicable.

Table 7.5 Measurement location, time periods and patient gender type

Position Length of measurement period Patient Gender



6-bed bay 3 8 days Female

4-bed bay 4 7 days Female

Single room A 7 days Male / Female

Single room B 7 days Male / Female

Overall measurements of A-weighted equivalent sound pressure levels (LAeq) for 24 hours, night and

day time were recorded at each location and are shown in Table 7.6.

Table 7.6 Average LAeq for 24 hour, day and night time periods at each location

Position in ward Average of A-weighted equivalent sound pressure levels



Nurse station 54.5 55.8 48.6

4-bed bay 1 51.7 53.1 41.4

6-bed bay 3 51.0 53.6 41.8

4-bed bay 4 50.9 52.6 42.0

Single room A 55.1 56.8 44.6

Single room B 56.5 58.2 46.4

A summary of the day and night time average levels presented in Table 7.6 are presented graphically

in Figure 7.21 for clarity. As with the medical ward, all levels in patient accommodation exceed those

suggested in the WHO guidelines without exception. It can be seen that day time and night time levels

measured in bays 1, 3 and 4 are very similar with an average night time drop of 11 dB. As found in

the medical ward, single patient rooms are less consistent both during the day and night.


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113

0

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45

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55

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Nurse station 4-bed bay 1 6-bed bay 3 4-bed bay 4 Single room A Single room B

Sou

nd

Pre

ssu

re (

dB

A)

Day time LAeq, 16hr

Night time LAeq, 8hr


Detailed results of levels measured at the nurse station are discussed in the next section, with further

results from the multi-bed bays shown in Section 7.8.2 and from the single rooms in Section 7.8.3.

7.8.1. Nurse station

Figure 7.22 shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours for the nurse station.

20

30

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70

So

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Aeq

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Time (24h:00)

Nurse Station LAeq Nurse Station LA90

Night time

Day time



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114

As with the nurse station in the medical ward, noise levels increase steadily from around 04.30 and do

not decrease substantially until late, around 23.30. Night time background levels are very consistent

at around 30 dB LA90, while day time background levels are around 40 dB LA90, with a temporary peak

at around 14.00 during the afternoon shift handover and the second round of patient admissions.

Levels begin to decrease from around 19.30.

Sources of high level noise seem to differ slightly from those captured at the nurse station in the

medical ward. Here, analysis of the trigger files indicates that the nurse call was used much more

frequently. This was confirmed by staff and patient responses to the questionnaire surveys, discussed

in Sections 7.9.1 and 7.9.2 respectively. High level conversation was also the source of many trigger

files, but unlike the medical ward high level noise due to furniture scraping on the floor was minimal.

Administrative tasks involving the use of ring binders also created a number of trigger files especially

during the night. This is further illustrated in Figure 7.23, which shows a number of peaks caused by

the closing of ring binders over a 30 minute period.

Figure 7.23 LAmax,2s (green trace) and LAeq,2s (red trace) measured over a thirty minute interval

during the night, from 2.40am, at the nurse station

Figure 7.24 shows an example of the nurse call captured with the microphone approximately 2 m

away from the main desk area. In this particular instance the nurse call was activated for over eight

minutes before it was reset. Each intermittent tone measured 70.4 dB LAmax, with an overall LAeq of

59.5 dB.

RING BINDER


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115

Figure 7.24 LAmax,2s and LAeq,2s fluctuating over a 11 minute interval at the nurse station

Further examples of high level noise levels captured at the nurse station, are presented in Table 7.7

below. It should be noted that the levels shown are the levels of individual events and so may not be

representative of every noise of that type.



Nurse call 70.4; 72.7

Internal phone 76.8

Ring binder 82.6

Door banging further down ward corridor 70.6

It can be seen in Table 7.7 that the closing of a ring binder generates noise at levels as high as 82.6

dB LAmax. As much of the administrative work is carried out by staff during the night when the ambient

noise level on the ward is low, this activity is likely to cause disturbance to those patients in the bay

opposite the nurse station.


Figure 7.25 shows the averaged LAeq,1hr levels over 24 hours for one 6-bed and two 4-bed bays and

the average background level (LA90,1hr) of all bays. It can be clearly seen that levels for the measured

bays are very similar and follow the same general pattern of fluctuation, with night time levels falling to

around 37 dB LAeq, and day time level remaining steady at around 53 dB LAeq. The average

background level varies from around 32 dB LA90 at night to around 40 dB LA90 during the day, similar to

three of the multi-bed bays in the medical ward.

INTERMITENT

NURSE CALL LAmax,2s

LAeq,2s


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116

Figure 7.25 also shows that, as in the medical ward, the WHO day / night division is not a particularly

good fit. Noise levels increase steadily from around 05.30 rather than 07.00, and begin to decrease

after the evening meal is served and then further decrease at 23.00. This suggests it might be

appropriate to redefine the ‘day’ and ‘night’ time periods for hospital noise assessment and perhaps

consider the addition of an ‘evening’ period.

The similarity of the measured levels between the 4-bed and 6-bed bays suggest, as with the medical

ward, that an increase in ward size from four to six patients does not necessarily affect the noise

levels. The consistency of the levels indicates that the daily ward routines which contribute to the

noise levels are comparable.

20

30

40

50

60

70

So

un

d P

ressu

re (

dB

LA

eq

,1h

r)

Time (24h:00)

4-Bed Bay 1 6-Bed Bay 3 4-Bed Bay 4 Average LA90

Night time Day time

WHO GUIDELINES

Figure 7.25 Average LAeq,1hr for each multi-bed bay and combined average LA90,1hr level for all bays

over 24 hours


Noise levels were measured in two single rooms. Figure 7.26 shows the average measured LAeq,1hr

levels over 24 hours and the average background level (LA90,1hr) of both rooms. To allow for

comparison with levels measured in the multi-bed bays, the average LAeq,1hr and the average

background level (LA90,1hr) of all the multi-bed bays are also shown on the graph.


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117

20

30

40

50

60

70

So

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d P

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dB

LA

eq

,1h

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Time (24h:00)

Single room A LAeq Single room B LAeq Multi-bed bay average Average LA90 - Single Rooms Average LA90 - Multi-bed bays

Night time Day time

WHO GUIDELINES

Figure 7.26 Average LAeq and LA90 levels for single rooms A and B and multi-bed bays

It can be seen that, as in the medical ward, noise levels measured in both single rooms are consistent

higher than those measured in the multi-bed bays. Background levels (LA90,1hr) are also higher, with

levels around 2 dB higher at night and as much as 4 dB higher during the day.

The patient in single room B had been on the ward for some weeks and seemed to enjoy chatting to

staff and her numerous visitors. As well as noise generated as a result of her clinical care, much of

the high level noise in this room was caused by conversation. This was particularly noticeable

between 15.00 and 20.00, where it can be seen in Figure 7.26 that noise levels consistently exceed

those measured in single room A. This is due to high levels of conversation during visiting time.

In single room A conversation was again responsible for a percentage of high level noise, but medical

equipment alarms also had an impact in this room. One particular type of alarm often generated high

level noise with its intermittent 30 second bleep. An occurrence of this was found to continue for over

two hours and a half hours before it was reset, with each bleep measuring close to 75 dB LAmax . The

effect of this is further illustrated in Figure 7.27.


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118

Figure 7.27 LAmax,2s (green trace) and LAeq,2s (red trace) showing the noise levels due to a medical

equipment alarm over a 13 minute period

Single room A is situated directly behind the nurse station. As discussed previously, doors to the

single rooms are generally left open to allow for easy observation of the patient. Staff talking, the

nurse call and internal phone ringing can all be heard clearly in the background from this bay, with the

nurse call measured at levels around 67 dB LAmax, and the internal phone measured at levels around

53 dB LAmax..




show the average number of high level noise events during the day and night in different

measurement locations.

It can be seen that the numbers of high level noise events in single room A during the day exceed

those in all other locations, with, on average, almost 500 events with LAmax between 70 and 75 dB;

around 150 events with LAmax between 75 and 80; and 30 events with LAmax above 80 dB. As

discussed in the previous section, these high level events are partly due to conversation with staff and

visitors, but are also impacted to a large extent by a particular piece of medical equipment with a high

pitched alarm. Alarms generally sound when equipment requires some kind of attention, for example

fluid levels are becoming low. Staff are obviously aware of the length of time they have before they

need to respond to an alarm; however, in this case one occurrence of this high pitched intermittent

bleep was observed to continue for over two and a half hours. This must have been annoying to the

patient, who was trying to rest after an undergoing an operation on the previous day. Perhaps if this

alarm had been in a multi-bed bay it may have been attended to sooner, especially if other patients

were annoyed by the noise and alerted staff.

INTERMITTENT BLEEP

OF MEDICAL

EQUIPMENT ALARM


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119

The differences in numbers of high level noise events between locations emphasise the limitations of

using only LAeq levels to describe the noise climate of hospital wards. In terms of LAeq,1hr room B has

higher levels (see Table 7.6 and Figure 7.26) yet in terms of individual high noise events Figure 7.28

shows that room A is ‘noisier’.

0

50

100

150

200

250

300

350

400

450

500

4-Bed Bay 1 6-Bed Bay 3 6-Bed Bay 4 Single room A Single room B Nurse Station

Nu

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hig

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nts

70 ≤ LAmax < 75 dB

75 ≤ LAmax < 80 dB

80 ≤ LAmax < 85dB

85 ≤ LAmax < 90dB

90 ≤ LAmax < 95 dB

Figure 7.28 Average number of high level noise events captured at each location per day

Many high level noise events can also be seen in single room B, with over 400 events with LAmax

between 70 and 75 dB; over 200 events with LAmax between 75 and 80; and around 80 events with

LAmax above 80 dB. When first admitted onto the ward, the patient in this room had been put in a multi-

bed bay. Here she had enjoyed talking to fellow patients and was disappointed when she was moved

into a single room, feeling more cut-off. This lady took every opportunity to chat with staff and visitors

for company which caused the majority of the high level noise events.

Although, as discussed in Section 7.8.2, overall noise levels in bays 1, 3 and 4 are shown to be

similar, differences can be seen between the bays in the numbers of high level noise events. As in the

medical ward, bay 1 is opposite the ward clerk’s desk, kitchen and staff room. Noise events from

these areas have been shown to impact the noise environment of this bay; this is further confirmed by

patient responses to questionnaire surveys, discussed in Section 7.11.

Unlike the medical ward the numbers of high level noise events captured in bay 3, which is opposite

the nurse station, were the lowest. This further confirms the fact that noise from the nurse station is

having a minimal impact on the noise levels in this bay.


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120

More sources of high level noise were captured at the nurse station on the surgical ward. As

discussed in Section 7.8.1 many of these were due to conversation. The nurse call also appeared to

be used more in this ward. The surgical ward is very different to the medical ward in terms of timings,

logistics and planning of operations. It is unsurprising to find more discussion at this nurse station as

the general pace of this ward is more frenetic than that of the medical ward.

0

10

20

30

40

50

60

70

80

90

100

110

4-Bed Bay 1 6-Bed Bay 3 6-Bed Bay 4 Single room A Single room B Nurse Station

Nu

mb

er

of

hig

h l

ev

el n

ois

e e

ve

nts

70 ≤ LAmax < 75 dB

75 ≤ LAmax < 80 dB

80 ≤ LAmax < 85dB

85 ≤ LAmax < 90dB

Figure 7.29 Average number of high level noise events captured at each location per night

Figure 7.29 shows that the numbers of high level noise events during the night are generally much

lower than those observed in the medical ward. This is mainly due to the differences in the numbers

of instances of patients crying out, which was very noticeable in the medical ward. This is further

confirmed by patient responses to questionnaire surveys, discussed in Section 7.9.2.


Staff response was good in the medical ward with 18 questionnaires completed, but response in the

surgical ward was rather poor, with only seven staff completing the survey. The following section

discusses results from the staff questionnaires and examines the differences between perceptions on

the medical and surgical wards.

Information regarding the design of the questionnaire surveys can be found in Section 5.4.



of the 18 respondents on the medical ward only two were male, and all seven respondents in the

surgical ward were female.


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121

The ages of the respondents in the two wards are shown in Figure 7.30. It can be seen that in both

wards the respondents are generally younger than 50, with a higher percentage of young staff

members completing the questionnaire in the medical ward.

0

5

10

15

20

25

30

35

40

45

50

20 - 30 31 - 40 41 - 50 51 - 60 60+

Pe

rce

nta

ge

of

resp

on

de

nts

(%

)

Age band (years)

Medical

Surgical

Figure 7.30 Age of respondents by band

Questions were asked in relation to the length of time worked both on the ward and at the hospital,

and the responses can be seen in Figures 7.31 and 7.32 respectively. What is clear is that staff

turnover in the surgical ward appears to be relatively low, with nearly 60% of respondents having

worked on the ward for over five years. The medical ward was more mixed, with an influx of new staff

(~40%) in the last year. It also appears some staff had transferred from other wards within the hospital

during their career.

0

10

20

30

40

50

60

Less than

1 year

1 - 2

years

2 - 3

years

3 - 4

years

4 - 5

years

5+ years

Pe

rce

nta

ge

of

resp

on

de

nts

(%

)

Time worked on the ward

Medical

Surgical

0

10

20

30

40

50

60

70

80

Less than

1 year

1 - 2

years

2 - 3

years

3 - 4

years

4 - 5

years

5+ years

Pe

rce

nta

ge

of

resp

on

de

nts

(%

)

Time worked on the hospital

Medical

Surgical

Figure 7.31 Time worked on the ward Figure 7.32 Time worked at the hospital



annoyed by noise. Figure 7.33 shows that the highest percentage of staff in the medical ward were

moderately annoyed by noise (43%), but this was not the case in the surgical ward, where the

majority (56%) of those questioned felt only slightly annoyed by noise.


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0 10 20 30 40 50 60

Not at all

Slightly

Moderately

Very much

Extremely

Percentage (%)

Surgical

Medical

Figure 7.33 Staff perception of noise in terms of annoyance



rated a noise event with a 2, 3 or 4, and as such could be said to be more than a little annoyed by the

event.

It can be seen that the most annoying noise events for the staff on the medical ward were visiting

time, medical equipment alarms and the internal telephone. This is similar for the surgical ward,

except that there the nurse call is also rated by a high percentage of respondents.

Discrepancies of between 20% and 30% can be seen between the medical and surgical ratings for

cleaning, people talking and staff talking. These events were found to be annoying by staff on the

medical ward, but to a much lesser extent in the surgical ward.


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123

0 10 20 30 40 50 60 70 80 90 100

External noise

TV / radio

Doors banging

Footsteps



Trolleys

Meal times


Nurse call

Rubbish bins

People talking

Cleaning

Internal telephone

Medical Equipment

Visiting time


Surgical (n=7)

Medical (n=18)

Figure 7.34 The percentage of staff rating an annoyance noise event with a 2, 3 or 4

Doors banging and external noise are rated more highly in the surgical ward. There is a particular

heavy, ill-fitting fire door at the end of this ward that was mentioned during initial discussions with the

ward manager. When this door bangs shut the noise appears to travel down the full length of the ward

corridor. With regards to the external noise; the surgical ward was surveyed during the summer

months when the weather was warmer, whereas the medical ward was surveyed in the spring. This

may account for the difference in external noise annoyance, as more windows may have been open

in the warmer weather.

For 10 out of 16 noise sources, the percentages of those annoyed on the surgical ward are higher

than on the medical ward. This could of course be simply down to the smaller sample size, and the

possibility that only those staff who felt strongly about noise felt inclined to complete the

questionnaire. However, other factors could also account for this difference. Medical and surgical

wards are different, and as such may attract staff with certain personalities. Surgical wards are very

busy with constant admissions for day or even half day procedures. Operations are booked in

advance and efficiency and timing are key. Medical wards are slower paced and it is possible that

staff annoyance of particular events could be less extreme.


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7.9.3. Interference with work

Respondents were asked to what extent noise interfered with their ability to work effectively. As can

be seen in Figure 7.35, opinions of the respondents in the surgical ward were very split, whereas the

majority of medical ward staff chose ‘slightly’ or ‘not at all’.

0 10 20 30 40 50

Not at all

Slightly

Moderately

Very much

Extremely

Percentage (%)

Surgical

Medical

Figure 7.35 Staff perception of the extent to which noise interferes with work


job effectively (again the rating scale of 0 to 4 was used). Figure 7.36 shows the percentages of staff

who rated a noise event with a 2, 3 or 4, and as such it could be said that this noise event interfered

to some extent with their ability to carry out their job effectively.

0 10 20 30 40 50 60 70 80 90 100

External noise

Meal times

Doors banging

Footsteps

Cleaning

TV / radio


People talking

Rubbish bins

Trolleys


Nurse call


Internal telephone

Medical Equipment

Visiting time


Surgical (n=7)

Medical (n=18)

Figure 7.36 The percentages of staff rating an interference noise event with a 2, 3 or 4


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125

As with the noise annoyance ratings, visiting time, medical equipment alarms and the internal

telephone were all rated as interfering with work by over 40% of respondents in each ward.

There are several anomalies worth noting. The nurse call is once again rated by a high percentage of

surgical staff as well as the trolleys and meal times; however these are not rated by a high percentage

of medical staff. Trolleys are used in both wards a great deal, but in the surgical ward patients are

often being wheeled through the ward to and from surgery and X-ray so trolley noise may be more

disruptive. It is unclear why meal times would be more disruptive in the surgical ward.





Figure 7.37 shows the mean ratings for each noise event. It can be seen that ‘conversations with

colleagues’ closely followed by ‘conversations with patients’ were considered by staff in both wards to

be the most important noise events. However, the average ratings were consistently high in all cases

suggesting that all of these events are important for staff. As with the annoyance and interference

ratings in the previous sections, staff in the surgical ward rated most events as more important than

those in the medical ward, but a similar pattern can be seen.

0

1

2

3

4

Nurse call Conversations

with colleagues

Conversations

with patients

Medical

equipment

alarms

Patients calling

out

Patient activity

Surgical (n=7)

Medical (n=18)



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126

7.10. Results of the patient questionnaire surveys

With the help of the ward clerks, questionnaires were distributed to those patients who had been on

the ward for over 24 hours and were judged to be physically and mentally fit enough to complete the

survey. In total 40 patients completed the questionnaire in the medical ward and 42 in the surgical

ward.

The following sections discuss results from the patient questionnaires and examine the differences

between perceptions on the medical and surgical wards.

7.10.1. Patient profiles

As with the staff questionnaire, the first section aimed to establish certain attributes about the

patients, beginning with gender. As discussed previously, the surgical ward was predominantly

female, and the medical ward predominantly male. This is shown clearly in Figure 7.38 below.

0

10

20

30

40

50

60

70

80

90

Male Female

Pe

rce

nta

ge

(%

)

Medical ward (n=40)

Surgical ward (n=42)

Figure 7.38 Gender split by ward type

Figure 7.39 shows the respondents’ age ranges. It can be seen that a relatively high percentage of

patients were aged 60 or above, with 70% in the surgical ward and 40% in the medical ward in this

age range.

0

10

20

30

40

50

60

70

80

20-30 31-40 41-50 51-60 60+

Pe

rce

nta

ge

(%

)

Age range

Medical ward (n=40)


Figure 7.39 Patients age by band


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127

Patients were asked how long they had been on the ward. Some differences can be seen between

the surgical ward and medical ward in Figure 7.40 below. Nearly 80% of respondents in surgical were

short term patients, having been on the ward for less than one week. It can be seen that the variation

in the medical ward was more marked.

0

10

20

30

40

50

60

70

80

90

< 1 week 1- 2 weeks 2 - 3 weeks 3+ weeks

Pe

rce

nta

ge

(%

)

Length of stay

Medical ward (n=40)


Figure 7.40 Length of patient stay when completing the questionnaire

Hearing impairment was also explored, with 24% of respondents on the medical ward and 17% on the

surgical ward indicating that they did suffer to some degree

The bed number of the respondent was noted on the front of the questionnaire by the ward clerk. This

number provided useful location information which is considered when investigating relationships

between bed positioning and patient accommodation type with day time noise annoyance and night

time disturbance, which are explored in Chapter 11. In terms of the single room / multi bed bay split,

91% of respondents in the medical ward were in multi-bed bays, with 83% in the surgical ward.

7.10.2. Noise annoyance and disturbance

The next section of the questionnaire considered day time noise annoyance and night time

disturbance. The questionnaire sought to identify the sources of noise that may annoy or disturb

patients. Respondents were given two lists of noises and were asked to rate the day time annoyance

and night time disturbance on a scale of 0 to 4 (where 0 indicated no annoyance / disturbance and 4

indicated a great deal). Several lines were left blank at the bottom of the lists for patients to add and

rate additional noise sources.

Patients were first asked how they perceived the day time noise environment on the ward. Figure 7.41

details the responses, which are fairly split between ‘quiet’ and ‘a little noisy’. Interestingly, when

asked whether they were actually annoyed by noise, only 13% of patients in the medical ward felt

annoyed, and 29% of patients on the surgical ward.


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128

0 10 20 30 40 50 60

Very quiet

Quiet

A little noisy

Very noisy

Extremely noisy

Percentage (%)

Surgical (n=42)

Medical (n=40)

Figure 7.41 Patient perception of the day time ward noise environment



and 4 indicating ‘a great deal’. With a relatively small number of people annoyed by day time noise

the sample set was low (n=5 for the medical ward and n=11 for the surgical ward). Figure 7.42 shows

the percentage of patients within these samples who rated a noise event with a 2, 3 or 4, and as such

could be said to be more than a little annoyed by the event.

It can be seen that patients crying out, trolleys, internal telephones and rubbish bins (to a certain

degree) appear to be sources of annoyance in both wards. One particular difference is the doors

banging, rated by nearly 60% of patients on the surgical ward, but no one on the medical ward. As

discussed in the staff questionnaire section, there is one particularly heavy fire door at the end of the

ward corridor which was mentioned as a problem in initial discussions with staff.

Other noticeable differences are the annoyance caused by visiting time, footsteps, nurse call and

external noise. All these events are only cited by patients in the surgical ward. Due to the nature of

the surgical ward, with patients being taken up and down to X-ray and surgery, this may account in

part to the increased annoyance caused by footsteps. Occurrences of the nurse call were captured

more often and continuing for longer periods at the nurse station in the surgical ward (see Section

7.8.1), which explains the patient responses in this case. As discussed previously, external noise may

be more of a problem during the study period in the surgical ward as the weather was warmer and

more windows would have been open.

Talking on mobile phones and TV / radio are the only events that are cited by medical patients only.

This could be due to a lack of enforcement of mobile phone policy, and the non-compulsory use of

headphones.


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129

0 20 40 60 80 100

External noise

Doors banging

Nurse call

Footsteps

Visiting time


Medical Equipment

People talking

Cleaning

Rubbish bins

Meal times

TV / radio



Internal telephone

Trolleys

Patients crying out

% of patients who rated each event 2 or above in terms of noise annoyance

Surgical (n=11)

Medical (n=5)

Figure 7.42 The percentage of patients rating an annoyance noise event with a 2, 3 or 4

Two patients in the medical ward added an additional noise event that they themselves found to be

annoying. The events were ‘a patient attention seeking’ and ‘the fan in the shower room’ (this was an

ensuite shower room in a single room). ‘Sirens’ and ‘the photocopier in corridor being used in the

evening’ were cited in addition by patients in the surgical ward.

Patients were asked how they perceived the night time noise environment on the ward. Figure 7.43

details the responses, where again the majority of the responses were split between ‘quiet’ and ‘a little

noisy’, but with a noticeably higher percentage (18%) in the medical ward choosing the ‘very noisy’

category than during the day.

When asked whether they were actually disturbed by noise at night, 58% of patients in the medical

ward felt they were, compared with 51% of patients on the surgical ward. This suggests that, in this

hospital, over 50% of patients are disturbed by noise at night.


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130

0 10 20 30 40 50

Very quiet

Quiet

A little noisy

Very noisy

Extremely noisy

Percentage (%)

Surgical (n=42)

Medical (n=40)

Figure 7.43 Patient perception of the night time ward noise environment



indicating ‘a great deal’. Sample sets were higher than for the day time annoyance (n=23 for the

medical ward and n=19 for the surgical ward), indicating a much higher level of night time

disturbance. Figure 7.44 shows the percentages of patients within this sample who rated a noise

event with a 2, 3 or 4, and as such could be said to be more than a little disturbed by the event.

One noticeable difference that can clearly be seen is that ‘patients crying out’ seems to be much more

of a problem on the medical ward during the night. This is possibly related to the number of elderly

patients suffering from confusion and dementia on this ward, who tend to cry out more often.

It can be seen that certain events which were rated as annoying by only patients in the surgical ward

during the day, cause a level of night time disturbance in both wards. Doors banging, medical

equipment, trolleys and people talking are rated by similar percentages of patients on both wards.

However, the nurse call, the internal telephone and external noise are all rated as more disturbing on

the surgical ward. Occurrences of the nurse call were captured more often and continuing for longer

periods at the nurse station in the surgical ward, which explains the patient responses in this case.

As discussed previously, external noise may have been more of a problem during the study period in

the surgical ward as the weather was warmer and more windows would have been open.

As with daytime annoyance, ‘Talking on mobile phones’ is cited as a disturbance only on the medical

ward. The hospital policy specifies that mobile phones should only be used in the lobby areas and not

on the wards. This suggests a lack of policy enforcement by the staff on the medical ward.


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131

0 10 20 30 40 50 60 70 80 90 100

External noise

Footsteps

Rubbish bins

TV / radio


Internal telephone


Nurse call

Trolleys


People talking

Medical Equipment

Doors banging

Patients crying out

% of patients rating night disturbance event of 2 or above

Surgical (n=19)

Medical (n=23)

Figure 7.44 The percentage of patients rating a disturbance noise event with a 2, 3 or 4

Six patients in the medical ward added an additional noise event that they themselves found to be

disturbing at night. The events were:

� Moaning, groaning and talking in sleep

� Dripping taps

� Noisy bed neighbours

� A patient admitted at night

� Private conversations between night staff, especially in native language

� Night staff having private conversations on mobile phones

One patient in the surgical ward also added ‘the supply cupboard door’ as an additional noise event.

This door had been mentioned by staff as a source of noise as it was a heavy metal roller shutter.


Looking at sound in a positive rather than in a negative light, patients were asked if there were any

sounds that they actually found comforting. 70% of patients in the medical ward and 76% on the

surgical ward left the answer blank; however, there were twelve completed responses, which included

listening to music on the radio, knowing that the nursing staff were nearby to provide care, the tea

trolley, and maintaining some connection with the outside world. The full responses can be seen in

Appendix B.


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132

Respondents were also asked if they felt that there was ever too little sound in a room. Only 8% of

patients in the medical ward and 8% in the surgical ward said that they did. Surprisingly only one of

these respondents was in a single room.

7.10.4. Ease of hearing and privacy

Patients were asked whether high levels of background noise may at times make it difficult to hear

doctors and nurses who talk to them. 27% of respondents on the medical ward and 36% on the

surgical answered that this was the case.

Conversational privacy was investigated by asking whether the patients felt that they could have a

private conversation at their bedside. 100% of patients in single rooms said that they felt they could

speak privately, with lower percentages in the multi bed bays of 67% and 64% in the medical and

surgical wards respectively. Out of those who felt they could speak privately, around 40% said they

felt they could talk in their normal voice, with 60% needing to lower their voice or taking some other

precautionary measure – similar percentages were found in both wards.

7.11. Questionnaire comments

Staff and patients were invited to make additional comments at the end of the questionnaire if they

wished. Very few staff made comments, but many patients did leave some feedback which was very

varied. Several patients cited the kitchen and ward entrance as a source of noise, and one patient

suggested that the ward clerk’s desk, which acts as a ward reception, should be moved outside the

ward entrance. Mobile phones ringing in the night, large groups of visitors around a bed and loud and

aggressive patients were also mentioned. A detailed list of these comments is shown in the Appendix

B.

7.12. Summary

This section summarises the main findings from the study of the medical and surgical ward at Bedford

Hospital:

� Average noise levels measured at the nurse stations on both wards were similar both in level and

fluctuation patterns, with day time levels of around 55 dB LAeq. However, sources of high level

noise were found to differ, with the nurse call and high levels of conversation more prevalent at

the nurse station in the surgical ward, and furniture scraping and doors banging found more

frequently at the nurse station in the medical ward.

� Noise level measurements made in the multi-bed bays were very consistent in both level and

fluctuation patterns in both wards, except for 6-bed bay 3 in the medical ward where the levels

were higher. Patients crying out and increased clinical activity were found to account for these

increased levels.


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133

� Levels did not appear to be affected by increased bed numbers, that is, from four beds to six

beds.

� Single rooms were found to have less consistent patterns of noise levels and often had higher

levels than those measured in multi-bed bays. Behaviour of patients, visitors and clinicians was

shown to be the main cause.

� All measured levels were above those suggested by the WHO guidelines and the day / night

division specified by the WHO did not appear to be realistic.

� Although average noise levels were similar, subsequent investigation of the numbers of high

level noise events recorded in each bay indicated differences in the noise climate. For example,

in both wards, bay 1 is shown to be affected by noise from the ward kitchen, staff room and

particularly the ward clerk’s desk area. Questionnaire responses were found to reinforce this.

� Staff in both wards rated visiting time, medical equipment alarms and the internal telephone as

the most annoying noise events. Cleaning, people talking and staff talking were found to be more

annoying by staff on the medical ward, whereas the use of the nurse call, banging doors, trolleys

and external noise were found to be more annoying by staff on the surgical ward.

� Only 13% of patients on the medical ward, and 29% of patients on the surgical ward were

annoyed by noise during the day. Patients crying out, trolleys and internal telephones were the

main sources of day time annoyance on both wards, with doors banging, visiting time, footsteps,

the nurse call and external noise only cited by patients on the surgical ward.

� Higher percentages of patients were disturbed by noise at night, with 58% in the medical ward

and 51% in the surgical ward. The main differences found between the night time ward

environments were patients crying out and mobile phone use in the medical ward, and the use of

the nurse call, internal telephone and external noise in the surgical ward.

7.13. Conclusions

Noise level measurements and questionnaire surveys have confirmed that noise is a problem in both

medical and surgical wards. Staff responses indicate that they are annoyed by noise, and over half

the patients questioned felt that they were disturbed by noise during the night, a time when they

should be able to rest and recuperate.

The identification of high level noise sources has shown that in this hospital building the ward design

does appear to have a negative effect on patients located in some of the bays and rooms, specifically

bay 1 and the single rooms behind the main nurse station. By re-siting the ward clerk’s desk and

ensuring doors to the kitchen and staff room are kept closed, much of this unwanted sound could be

prevented. However, the two single rooms located directly behind the main nurse station is a more

difficult problem to address, with doors to the rooms left open to allow for patient observation.


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134

Noise levels did not appear to be related to occupancy levels, with similar levels measured in four and

six bed bays, and higher levels measured in single patient rooms than in multi-bed bays on

occasions.

Much of the high level noise identified could be reduced with changes to behaviour, correct

enforcement of hospital policies, simple improvements to design and maintenance of equipment. This

is discussed further in Chapter 12.

The following chapter investigates the effects of a refurbishment carried out in the medical ward at

Bedford Hospital. Reflective ceiling tiles in one four bed bay were changed for tiles with good acoustic

properties. Subsequent changes to noise levels and reverberation times are investigated and

reported.

Acoustic Design for Inpatient Facilities in Hospitals Ceiling intervention study

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135

8. Ceiling intervention study, Bedford Hospital

8.1. Introduction

The medical ward in Bedford Hospital was due for refurbishment soon after the objective

measurements and subjective surveys (discussed in Chapter 7) were completed. This was to include

the replacement of the suspended ceiling tiles; a full repaint of all rooms; replacement of protective

wall panelling; and some general tidying and maintenance work.

Much of the existing suspended ceiling in the ward was known to have good acoustic properties, but

the large perforations in the tiles were felt to be unsuitable in light of the current control of infection

policy. Tiles of similar acoustic properties are now available on the market designed specifically for

hospital use. These tiles have a smooth finish and can withstand the bleaches and detergents

commonly used in hospital cleaning regimes. The author, working in conjunction with the hospital

estates team, suggested that these replacement ceiling tiles should be considered throughout the

ward. Although the tiles were slightly more expensive than the standard plain plaster tiles, the

purchase was agreed.

One bay was of particular interest to both the Estates team and the author. This bay had been

refurbished more recently than the rest of the ward and had a suspended ceiling of plain plaster type

ceiling tiles with poor acoustic properties. It was considered by both parties to be an excellent

opportunity to study the effects of changing the ceiling tiles, on the acoustic environment. The results

could then be used by the estates team to inform their decision making for further ward

refurbishments. Figure 8.1 shows the bay during refurbishment.

Figure 8.1 Photographs of the bay during refurbishment


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136

The study of the effects of the ceiling change in this bay discussed in this chapter, consists of two

parts: firstly the investigation of the effects of the ceiling change on the noise levels; and secondly the

effects of the ceiling change on occupied and unoccupied reverberation times.

8.2. Bay information

Bay 1 is the first open four bed bay immediately after the main entrance to the medical ward, and is

opposite the ward clerk’s desk, the staff room and the kitchen, as shown in Figure 7.10 in Section 7.5.

This particular bay was refurbished several years ago with a change from the original acoustic ceiling

tile to ‘Armstrong Bioguard Plain’ tiles. Although suitable for hospital use, these tiles have poor

acoustic properties. Figure 8.2 shows the manufactuer’s data on absorption coefficients for octave

frequency bands from 125 Hz to 4 kHz.

Figure 8.2 Absorption coefficients of Armstrong Bioguard Plain ceiling tiles

Source : Manufacturer’s product specification sheet

During the ward refurbishment, these tiles were changed for ‘Armstrong Bioguard Acoustic’ tiles.

Figure 8.3 shows the manufactuer’s data on absorption coefficients in frequency bands from 125 Hz

to 4 kHz for this tile. It can be seen that these tiles provide much greater acoustic absorption than the

previous ones, with particular improvement in frequencies from 500 Hz to 4000 Hz.

Figure 8.3 Absorption coefficients of Armstrong Bioguard Acoustic ceiling tiles

Source : Manufacturer’s product specification sheet


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137

8.3. Effect of ceiling tile change on noise levels

As part of the main study, occupied noise levels were measured in bay 1 over two separate weeks

prior to the ceiling change, as discussed in Section 7.6.2. For comparison purposes, the microphone

was suspended in the same position following the ceiling change and a further two weeks of data

were collected and compiled.

The first set of noise level data was collected with the bay occupied by female patients in April and

June 2010. The post ceiling change data were collected during December 2010 with male patients in

the bay. Apart from the time of year and the patient gender, there were no other known changes on

the ward, apart from the ceiling tiles. All ward routines remained the same.

Before any meaningful comparisons could be made between the pre and post ceiling change

measurements, the data were analysed in detail to see if any anomalies were present. Each trigger

file (created when LAmax exceeded 70 dB) was reviewed and all files were grouped by event type. The

average number of triggers over a 24 hour period was calculated for each event type both pre and

post the installation of the new ceiling tiles. Two anomalies caused by untypical patient behaviour

were identified and were considered to be worth further investigation: unusually high numbers of

triggers caused by patient cries during the pre ceiling change period; and the amount of coughing

after the ceiling change.

Further analysis of the trigger files showed that during the pre ceiling change measurement period

there was a very confused elderly lady in the bay who screamed whenever staff tried to sit her up or

get her out of bed. This caused a total of 278 individual triggers files (201 during the day and 77 at

night) over the period of one week which caused a increase in overall noise levels. It was felt that this

was an untypical event as there were no other episodes of this type during the subsequent weeks of

data collection. Therefore, to ensure that the data was comparable, this particular event was removed

for the analysis of noise levels.

The noise level measurements made after the ceiling change were carried out in December. This was

a particularly cold month and patients coughing caused a large number of trigger files during the

measurement period (on average more than 120 triggers were caused by coughing over 24 hours

compared with an average of 20 over 24 hours during the pre ceiling change period). As the ward was

not one that dealt with chest infections this was felt to be untypical of the noise climate on this ward. It

was decided that to provide a more realistic data comparison, the high numbers of coughs in the data

should be reduced to the average number found during the pre ceiling change period.

With the anomalies in the data removed, overall noise levels were calculated. Table 8.1 shows the

average LAeq measured during the day and night time pre and post the ceiling change. It can be seen

that day time and night time levels after the ceiling change are on average 2.4 dB and 3.4 dB LAeq

respectively lower than levels before the change.


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138

Table 8.1 Average LAeq measured during the day and night time pre and post the ceiling change

Position in ward A-weighted equivalent sound pressure levels

Day time Night time

LAeq, 16hr LAeq, 8hr

Pre ceiling change (2 weeks) 53.7 45.2

Post ceiling change (2 weeks) 51.3 41.8

20

30

40

50

60

70

So

un

d P

ressu

re (

dB

LA

eq

,1h

r)

Time (24h:00)

Pre ceiling change Post ceiling change

Night time

Day time

Figure 8.4 Average LAeq,1hr levels over 24 hours pre and post ceiling change

Figure 8.4 shows the average LAeq,1hr levels measured over 24 hours pre and post the ceiling change.

Fluctuations in level follow the same pattern, suggesting that ward routines are unchanged, but the

levels are consistently lower.

The decrease in the overall measured noise levels suggests that the acoustic ceiling tiles are having

some positive effect. This can be further substantiated by looking in more detail at the high level noise

sources before and after the ceiling change, with the anomalies removed. Figure 8.5 shows the

number of high level noise events captured; that is events where LAmax exceeds 70 dB. Any notable

differences are highlighted.


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139

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Unidentifiable

Conversation between staff

Staff and patients talking

Patients talking

Patient talking on phone

Patient procedures

Cough / sneeze / gurgling / groaning / snoring

Rubbish bin

Laughter

Shoes squeaking on floor

Patient calling out

Furniture scraping

Ring binder / admin at nurses' desk

Cleaning

Cupboard door / drawers

Tea / drinks round

Meal time

Bathroom door

Trolley

Visiting time

Noise from corridor / kitchen

Mobile phone ringing

Average number of trigger files recorded in 24 hours

PRE ceiling change

POST ceiling change

Figure 8.5 Average number of trigger files recorded over 24 hours by event type

It can be seen in Figure 8.5 that there are notable reductions in the numbers of high level noise

events associated with visiting time, patient procedures and staff and patients talking. These events

include speech, a frequency range at which the new ceiling tiles are known to be particularly

acoustically absorbent which may explain these reductions. The numbers of high level noise events at

meal times and during cleaning are also reduced, as are the number of unidentifiable events.

Figure 8.6 shows the frequency content of a typical high level noise event associated with meal time,

that is, metal cutlery scraping on a china plate, which was recorded before the ceiling change. It can

be seen that the levels are higher at the low frequencies, decreasing steadily from around 150 Hz to

around 1 kHz, and then rising again in the frequency bands at which the ceiling tiles are most

effective. It is therefore unsurprising that the new ceiling tiles, which provide more absorption at high

frequencies, are having some positive effect on noise events of this type.

Figure 8.6 The frequency content of metal cutlery


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8.4. Effect of ceiling tile change on reverberation time


important measurement in the field of room acoustics. As discussed in Section 5.3.8, any RT

measurements made in unoccupied wards were carried out using the Impulse Response Method with

balloon bursts as the source of noise. In occupied wards, where physical RT measurements are not

possible, an estimation method is used. As explained in Chapter 1, data collected in this study have

been used to validate an estimation method developed at the University of Salford (Kendrick, 2009).

The validation is discussed in more detail in Chapter 10. The reverberation times for occupied wards

presented in this Section 8.4.2, have been estimated using this method.

8.4.1. Unoccupied reverberation times

RT measurements were carried out in the unoccupied bay using the Impulse Response Method just

prior to, and just after the ceiling tile change. In total twelve RT measurements were made, six before

the ceiling change and six after. Figure 8.7 shows the layout of source and receiver positions, with the

following combinations of source and receiver positions used: S1-R1; S2-R1; S3-R1; S1-R2; S2- R2;

S4-R2.

Figure 8.7 Source (S) and receiver (R) positions used to measure reverberation time in the

unoccupied bay before and after the ceiling change

Although the bay was unoccupied during the RT measurements, there was some furniture piled in the

centre of the bay on both occasions, as shown in the photographs in Figure 8.1. This may have

S1

S3

S2 S4

R1

R2


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141

provided some small amount of acoustic absorbency, but was in place during both sets of

measurements and as such may affect the overall RT values, but should not affect the differences.

Figure 8.8 shows the spatially averaged RT20 values over third octave bands from 250 Hz to 4 kHz as

stipulated in BS EN ISO 3382-2 (2008). The error bars show the 95% confidence limits of the mean

values. It can be seen that at all frequencies the measured RT20 values have decreased after the

ceiling tile change, by between 0.1 s and 0.4 s, with the greatest changes above 500 Hz. Given that

these are the frequencies at which the tiles have the highest absorption coefficients, these results are

as expected. The 95% confidence limits are generally small, particularly at the higher frequencies,

suggesting little variation between the measured values at each frequency.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

250 315 400 500 630 800 1 k 1.25 k 1.6 k 2 k 2.5 k 3.15 k 4 k

Me

an

RT

20

(s)

Frequency (Hz)

Pre ceiling change

Post ceiling change

Figure 8.8 Average unoccupied RT20 measurements with 95% confidence limits

(Impulse Response Method)

Bork (2000) shows that in a room with an RT value of 2 s or less, the subjective difference limens are

0.1 s, and hence any change in the RT that is less than 0.1 s would not be noticeable to the listener.

In this case however, the changes of between 0.1 s and 0.4 s exceed this difference limen, and as

such would be perceived by the occupants of the bay.

8.4.2. Occupied reverberation times

Using trigger files captured during the measurement period before and after the ceiling change,

reverberation times of the occupied bay were estimated using the Maximum Likelihood Estimation

Method (MLE-RT20) which is discussed fully in Chapter 10.

Over 5000 individual trigger files were processed to produce each octave band MLE-RT20 estimate

from 250 Hz to 4 kHz. As would be expected the estimated values for the occupied ward are lower

than the measured RTs in the unoccupied ward, by up to 0.3 s at 4 kHz both pre and post the ceiling


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change .This is due to the absorbency of the additional furniture, bedding, curtains and the occupants

themselves.

Figure 8.9 shows the estimated MLE-RT20 values before and after the ceiling replacement. As with

the values measured in the unoccupied bay, it can be seen that the addition of the acoustic ceiling

tiles has reduced the MLE-RT20 values by up to 0.1 s in each of the octave bands estimated. The

largest differences are in the 1 kHz to 4 kHz frequency bands, where the reduction in MLE-RT20 is

greater than 0.1 s. This is as would be expected as these are the frequencies where the new ceiling

tiles are particularly effective. The reduction in the MLE-RT20 estimate is much less at 500 Hz, and at

250 Hz the 95% confidence limits of the pre-replacement estimate are ±0.13 s and therefore the

results at this frequency should be ignored.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

250 500 1000 2000 4000

Est

ima

ted

MLE

-RT

20

(s)

Octave band (Hz)

Pre ceiling

replacement

Post ceiling

replacement

Figure 8.9 Occupied MLE-RT20 estimates pre and post the ceiling replacement,

8.5. Comparison of unoccupied and occupied RTs

The estimated MLE-RT20 values shown in the previous section not only reinforce the effect of the

ceiling tile change on the room acoustic, they also provide useful information regarding the amount of

acoustic absorption in an occupied four bed bay, and the effect that this extra absorption has on the

reverberation time. Tables 8.2 and 8.3 show the reverberation times measured in the unoccupied bay

alongside the estimated MLE-RT20 values when the bay is occupied, both before and after the ceiling

change.


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143

Table 8.2 Reverberation times for both the unoccupied and occupied bay pre ceiling change

Frequency (Hz)

Pre ceiling change - measured RT20 (s) in unoccupied bay

Pre ceiling change - estimated MLE-RT20 (s) in occupied bay

Decrease (s)

250 0.64 0.63 0.01

500 0.65 0.44 0.21

1 k 0.69 0.42 0.27

2 k 0.69 0.42 0.27

4 k 0.70 0.38 0.32

Table 8.3 Reverberation times estimates for both the unoccupied and occupied bay

post ceiling change

Frequency (Hz)

Post ceiling change - measured RT20 (s) in

unoccupied bay

Post ceiling change - estimated MLE-RT20 (s) in

occupied bay

Decrease (s)

250 0.51 0.39 0.12

500 0.42 0.33 0.09

1 k 0.29 0.27 0.02

2 k 0.36 0.29 0.07

4 k 0.38 0.27 0.11

It can be seen from Tables 8.2 and 8.3 that in the more reverberant room (pre ceiling change) the

difference in reverberation times at 1 kHz between the unoccupied and occupied space at 500 Hz and

above is greater than 0.2 s. However, with the ceiling changed, there is a negligible difference

between the unoccupied and occupied reverberation times at those frequencies. As discussed in

Section 8.4.2 the results at 250 Hz are unreliable and therefore this estimate should be ignored.

8.6. Conclusions

This chapter clearly illustrates the benefits of the installation of an acoustic ceiling, which results in

consistently lower measured average noise levels and a decrease in reverberation times (from 0.7 s

to 0.3 s at 1 kHz in the unoccupied room). Notable reductions in the numbers of high level noise

events associated with visiting time, patient procedures, conversation, meal times and cleaning were

also found after the ceiling change.

This intervention study has also provided interesting data regarding the level of acoustic absorption

provided by the occupants and soft furnishings in a 4-bed bay, with a reduction in the reverberation

time of over 0.2 s at most frequencies in the bay before installation of an acoustic ceiling. After the

addition of a large area of acoustic absorbency in the form of a ceiling, the effects on the room

acoustics of the occupants and soft furnishings becomes negligible.

The following chapter presents the results of the objective and subjective surveys at Addenbrooke’s

Hospital, Cambridge while Chapter 10 gives details of the method used to estimate the occupied RTs

and its validation using data collected from both Bedford and Addenbrooke’s Hospitals.

Acoustic Design for Inpatient Facilities in Hospitals Addenbrooke’s Hospital

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144

9. Addenbrooke’s Hospital

9.1. Introduction

Three wards at Addenbrooke’s Hospital also formed part of the subject of the main study which took

place over an eight month period from April to November 2010. To provide comparisons between

buildings of different age, construction type and ward layout, three wards were identified for the study

following liaison with the Estates team: a 1970’s tower block of brick and concrete construction; a

recently opened modular block of timber construction; and a privately funded building completed in

2006 and built to adhere to the latest acoustic design standards

The study wards also provided useful comparisons in terms of the types of patient accommodation

and care offered. Ward D8, situated in the 1970’s tower block, is a trauma and orthopaedic ward. This

ward is large and has a mixture of accommodation ranging from 3-bed bays through to a 12-bed bay.

Care is offered to a diverse group of patients; some with severe injuries as a result of road accidents;

some with injuries resulting from elective surgery; others suffering from both physical trauma and a

level of dementia. Ward N3, situated in the modular block, is a respiratory ward for both acute and

chronically sick patients and contains a specialist respiratory unit to care for patients who require non-

invasive respiratory ventilation. Accommodation provided here is a mix of single rooms and 4-bed

bays. Ward M4, situated in the privately funded Addenbrooke’s Treatment Centre, is a surgical ward

specialising in urology. Accommodation provided here is again a mix of single rooms and 4-bed bays.

9.2. Background

Addenbrooke’s Hospital opened in 1766 and was one of the first provincial, voluntary hospitals in the

UK. By the 1950’s the hospital had started to outgrow its original site and in 1959 building began on a

new 66-acre site south of Cambridge, with the first phase of the new hospital opening in May 1962.

Figure 9.1 Original building, Addenbrooke’s Hospital

Now, nearly 250 years after its inception, the hospital provides emergency, surgical and medical

services for people living in the Cambridge area and offers regional specialist services for organ


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145

transplantation, cancer, neurosciences, paediatrics and genetics. Bed numbers currently stand at

1200, with 7000 staff employed and annual inpatient admissions at around 180,000. The site now

includes a dedicated maternity and women’s hospital, The Rosie, with deals with around 5800 births a

year.

9.3. Ward D8 (surgical)

Ward D8 is situated on the eighth floor of the 1970’s tower block, known as C & D block. This is a

trauma and orthopaedic ward dealing with trauma as a result of an accident and performing elective

therapeutic interventions, for example, for problems caused by wear and tear to the hips, joints and

shoulders. The ward has total of 35 beds and is the second largest in terms of bed numbers on the

Addenbrooke’s hospital site. This ward is divided between three single rooms, three 3-bed bays, a 4-

bed bay, a 7-bed bay and a 12-bed bay.

Thirteen out of 35 patient beds on this ward are dedicated to care of elderly female patients. These

beds, collectively known as the ‘elderly trauma unit’, consist of two 3-bed bays and a 7-bed bay and

have the highest intervention of nursing on the ward, with four nurses to 13 patients. The unit treats

those over 75 years of age who have been involved in an accident, or for example, have broken their

hip as a result of a fall. Often these patients are suffering from a number of other complaints such as

confusion, dementia or delirium, and consequently this section is considered to be noisy by the ward

manager, with patients calling out and banging objects. Elderly male patients admitted to the ward are

placed in the standard male accommodation.

9.3.1. Building design

C & D block is a 10 storey naturally ventilated tower block constructed in the early 1970’s. Brick built

with cavity walls and concrete floors, it is unknown whether it was built to comply with any particular

acoustic standard. The building is a mirror image designed around a central lift shaft and stairwell,

with C section on one side and D on the other.

Internally, apart from general maintenance, the replacement of single glazed windows with double

glazed units, and some redecoration, very little has changed since the building was completed.

However the wards, which were originally built to house a total of 24 beds, now contain up to 35 beds.

Bed spacing is considered to be very poor, leading to a compromise in privacy and dignity. To

illustrate this lack of space further, the ward area of D8 is 850 m2 compared to 1250 m

2 in ward M4

which is situated in the recently opened, privately funded treatment centre, and provides only 28

patient beds.

The study ward, ward D8, has little in the way of acoustic absorbency at ceiling level. Most ceilings

consist of metal pan tiles which work in conjunction with the heating system, by radiating heat from

the hot water pipes running above them. These tiles are perforated, with a layer of insulation covering

the water pipes. This may provide some level of acoustic absorbency at certain frequencies, but this


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146

is unknown. An exception to this is the 4-bed female bay situated behind the nurse station, which has

a suspended ceiling grid with solid plaster tiles. Other acoustic absorbency on the ward is provided by

privacy curtaining which can be pulled fully around each bed; window curtaining; mattresses and

bedding. All patient accommodation has heavy duty vinyl flooring and solid plaster walls.

9.3.2. Ward layout

Senior staff offices and the main ward reception area are positioned in the central lobby area which

separates C and D wards. A card swipe system is in operation to allow access to ward D8, which is

designed around a long interior corridor, with the majority of patient accommodation on one side, and

a male 12-bed bay situated centrally at the end of the corridor. Healthcare utilities, a staff room, ward

kitchen, day room and three single rooms are situated on the opposite side. There is also a service lift

for patient transportation and ward deliveries. Ensuite toilets are provided in each bay, but single sex

bathrooms are situated at each end of the corridor. A ward plan is shown in Figure 9.2 on page 150.

The 12-bed and 3-bed bays at the end of the ward are male only. The male patients use the toilet and

bathroom facilities at this end of the ward corridor to ensure same sex segregation. There is a small

nurse station in the centre of this 12-bed bay, with a PC and telephone, which may be a source of

some noise, especially at night.

The main nurse station is situated directly outside the 4-bed female bay and opposite the three single

rooms. Again, a potential source of noise, this area is often bustling with staff and is where the ward

clerk is based during office hours.

The remaining bays house the ‘elderly trauma unit’, which are opposite the healthcare utilities, staff

room, and assisted bathroom and ward kitchen.

Compared to wards in newer buildings, such as M4 and N3 (the other study wards on this site), this

ward feels rather cluttered, with a general lack of storage space, and a narrow dark central corridor.


The doors to all bays are always left open for observation purposes, with single rooms generally used

for infectious patients. If barrier nursing is required, the doors to the single rooms are closed. The

ward runs at a very high occupancy level, of around 99%.

Staffing levels and shift patterns

Staffing levels are highest from 07.15 until 15.15, with ten nursing staff present, seven days a week.

This reduces to seven nursing staff for the afternoon shift and to six for the night shift, which lasts

from 19.15 to 07.15. Other staff members include a ward clerk who works during office hours from

Monday to Friday, and six therapists who work with the patients on weekdays and weekend mornings.

There are 13 consultants and seven registrars serving this ward. The doctors’ rounds generally take


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147

place in the morning and during this time there could be between eight and ten doctors on the ward.

At weekends the number of doctors drops to three.

Three domestic staff also work from 08.00 to 16.00, with an additional staff member working from

16.00 until 20.00. One of these staff members is dedicated to cleaning (moping, damp dusting,

changing beds and picking up litter); the other two are housekeepers and are more involved in serving

food, beverages and replenishing water jugs. The member of staff working the later shift plays a dual

role.

Ward routines

The first patient visits by clinicians are around 06.00 for general observation, dispensing of drugs and

theatre preparation. However, general activity on the ward does not begin until 06.50 when the main

lights are switched on.

Morning shift handover takes place between 07.15 and 07.45 in the day room, staff room and at the

main nurse station in the corridor. After the handover the night staff accompany the day staff to their

charges to discuss the patient’s progress and examine their notes. There can be as many as six

people at the end of the patient’s bed at this time.

From 08.00 onwards the ward is very busy with nurses attending to their patients and the arrival of

surgeons, therapists, domestic staff and the ward clerk. The ward does not begin to calm down again

until late morning when the nursing staff have a break from the patients and have a chance to catch

up on phone calls and other administrative aspects of their jobs.

From 14.00 until 15.00 there is a designated rest period on the ward which is primarily to help patients

get some rest before visiting time begins.

Drug rounds and patient observations continue throughout the day at noon, 17.00, and 21.00.

A second shift handover takes place when the night staff arrive, between 19.15 and 19.45. As with the

morning handover, the day and night staff visit their patients, check notes and discuss patient

progress.

The ward lights are finally dimmed around 23.00. During the night patients who are particularly unwell

have further observations taken at 02.00.

Meal times

A cold breakfast of cereal and toast is prepared in the ward kitchen and served from a trolley from

08.15 to 09.30. This is followed by a hot drinks trolley at 10.00. A hot lunch arrives on the ward at

midday and is plated up in the corridor. A selection of cold supper options is served at 17.00.


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148

Visiting times

The official hours for visiting time are 15.00 until 20.00.

Sources of noise on the ward

The following are thought to be the main sources of noise by the ward manager:

Doorbell

There is a buzzer but it is not felt that this is particularly loud

Nurse Call

This system has a changeable volume, but is never turned up very loud, even during the day.

Telephones / PCs / fax / printers

There are four telephones, three PCs, a fax and printer at the main nurse station, and other

telephones and PCs on staff desks in the larger multi-bed bays.

Patientline

This TV, radio and telephone system is available here at a cost. Headphones are provided and any

patient not using them would be asked to make use of them for watching TV or listening to the radio.

Medical Equipment Alarms

Plaster removal

No treatment room is available on this ward and plaster casts are removed at the bedside.

Deliveries

Ward deliveries come up to the ward via the service lift. Large deliveries, such as linen, are delivered

in wheeled cages and are generally left in the corridor. Smaller deliveries include pharmacy items.

9.3.4. Managing the study

The ward manager was very supportive of the study and made every effort to ensure that full

cooperation was provided by the ward staff. There were no undue concerns regarding the cleaning of

the noise measurement equipment and the ward manager spent several hours of his time identifying

possible microphone positions that would be acceptable to staff and patients. For comparison

purposes it was important that the microphone was placed in similar locations in each accommodation

type. A ward plan showing the microphone positions can be seen in Figure 9.2.

To avoid the microphone being knocked or contaminated, and in order for it to be as unobtrusive as

possible, it was felt that suspending the microphone from the ceiling would be ideal. An identical 300


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149

mm bracket to that used successfully at Bedford Hospital was used to suspend the microphone from

the ceiling at each measurement position.

Questionnaires were reviewed by the ward manager and it was decided that they would be distributed

by the ward clerk to those patients who had been on the ward for over 24 hours and were felt to be fit

enough to complete the survey. Staff questionnaires were to be left for staff to complete in the staff

room.

As with the pilot study, a number of laminated posters were displayed throughout the ward common

areas. These posters were aimed at both staff and patients and explained in simple terms why and

how the study was being undertaken. In addition to these posters the ward manager personally

discussed the study with all his staff during staff meetings.

Figure 9.2 Detailed plan of ward D8 showing microphone positions

Microphone position


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151

9.4. Overall acoustic survey results Ward D8

Noise level measurements were made at six different locations on the ward. Table 9.1 shows the

locations and the time periods of all measurements made, and the patient genders where applicable.

Unfortunately it was not possible to make measurements in the single rooms on this ward due to the

infectious conditions of the patients.

Table 9.1 Ward D8 - measurement locations, time periods and patient gender / types

Position Length of measurement period Patient gender / type


12-bed bay 2 non-consecutive weeks (14 days) Male

7-bed bay 6 days Elderly

4-bed bay 8 days Female

3-bed bay A 7 days Male

3-bed bay B 7 days Elderly

Overall measurements of A-weighted equivalent sound pressure levels (LAeq) were averaged and are

shown for 24 hours, day time and night time in Table 9.2.

Table 9.2 Average LAeq measured for 24 hour, day and night time periods at each location.

Position in ward Week average of A-weighted equivalent sound pressure levels



Nurses Station 57.0 58.1 52.9

12-Bed Bay Week 1 55.4 56.9 47.1

12-Bed Bay Week 2 56.4 57.9 48.2

7-Bed Bay 56.4 57.8 49.4

4-Bed Bay 54.3 55.6 48.5

3-Bed Bay A 55.0 56.5 47.1

3-Bed Bay B 56.5 57.8 50.7


in Figure 9.3 for clarity. As with the wards at Bedford Hospital, levels in all patient accommodation

exceed those suggested in the WHO guidelines without exception. Little variation can be seen within

the day and night time average noise levels for the patient accommodation, despite the wide range of

patient numbers (3 to 12), with day time levels ranging from 55.6 to 57.9 dB LAeq, 16hr and night time

levels ranging from 47.1 to 50.7 dB LAeq, 8hr. Day and night levels at the nurse station are, as expected,

higher than those measured in the patient accommodation.


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152

In terms of the drop in level between day and night, only a relatively small drop of 5 dB was observed

at the nurse station, which is comparable with nurse stations on the study wards at Bedford Hospital.

This is unsurprising as the nurse station is staffed at all times. The male bays showed the greatest

drop in level between day and night of around 10 dB, which is unexpected as one of the male bays

measured was the largest bay in the study, containing 12 beds. The elderly patient bays and female

bays showed a slightly lower day to night drop of around 7.7 dB, which could possibly be related to

patients crying out.

0

5

10

15

20

25

30

35

40

45

50

55

60

65

Nurses Station 12-Bed Bay 3-Bed Bay A 3-Bed Bay B 7-Bed Bay 4-Bed Bay

So

un

d P

ressu

re (

dB

LA

eq

,1h

r)

Day

Night



results from the multi-bed bays shown in Section 9.4.2.


Figure 9.4 shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours at the nurse station. It can be

seen that the lowest average ambient noise levels are recorded during the later part of the night,

where they are around 50 dB LAeq. From 05.30, levels increase steadily and peak at 11.30 when the

staff are free to catch up with administrative tasks and telephone calls and are therefore working at

the nurse station. Levels remain fairly constant at around 59 dB LAeq during the middle part of the day,

with a slight dip following lunch and during the patient rest period. Levels then begin to decrease

around 16.00, peaking briefly again during the evening shift handover and then do not decrease

substantially until 23.30. This pattern follows the ward routines described in Section 9.3.3. The night

time background levels remain very constant at around 42 dB LA90, while day time background levels

peak in the middle of the day at around 48 dB LA90.


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153

20

30

40

50

60

70

So

un

d P

ressu

re (

dB

LA

eq

,1h

r)

Time (24h:00)

Nurse station LAeq Nurse station LA90

Night time Day time


Viewing averaged noise levels over time, as in Figure 9.4 above, provides valuable information with

regards to level consistency and overall day and night time variation patterns, but does not illustrate

the fluctuating nature of noise in the short term. Figure 9.5 shows noise levels captured at the nurse

station over a ten minute time interval at 04.30 with the microphone approximately 1.5 m away from

the main desk area. Using the trigger files captured when LAmax exceeds 70 dB, certain high level

noise events have been identified.

Figure 9.5 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a ten minute interval at the

nurse station during the night

The sources of high level noise shown in Figure 9.5 are a good representation of types of high level

noise captured at this nurse station during the night and are predominantly related to the

RINGER

BINDERS DESK DRAWERS

SHUTTING

FURNITURE

SRAPING


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154

administrative tasks undertaken by the staff. Identified events consist mainly of the closing of ring

binders, furniture scraping on the floor and desk drawers shutting.

Day time high level noise at the nurse station was found to be mostly due to conversation, with some

noise again associated with administrative tasks and some occurrences of the internal phone.

Although in use on the ward, the nurse call system and doorbell were not captured as sources of high

level noise. As discussed in Section 9.3.3, the ward manager confirmed that the volume of both these

systems is deliberately turned down.






Furniture scraping 78

Ring binder 85; 90

Desk draw shutting 81

Internal telephone 68


Figure 9.6 shows the averaged LAeq,1hr levels measured over 24 hours for two 3-bed, a 4-bed, a 7-bed

and 12-bed bay. It is clear from the figure that although the numbers of beds in the bays vary

considerably, there does not to appear to be a relationship between bed numbers and noise levels,

with some of the highest levels measured in the elderly 3-bed bay. Interestingly, the largest bay (12

beds) actually shows one of the lowest averaged LAeq,1hr levels during the night.


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155

20

30

40

50

60

70

So

un

d P

ressu

re (

dB

LA

eq

, 1

hr)

Time (24h:00)

12-Bed Bay (Male) 7-Bed Bay (Elderly) 4-Bed Bay (Female) 3-Bed Bay (Male) 3-Bed Bay (Elderly)

Night time Day time

WHO GUIDELINES

Figure 9.6 Average LAeq,1hr levels over 24 hours for the multi-bed bays

The figure also shows that the WHO day / night division is not a particularly good fit. Noise levels


is served and then further decrease at 23.00. This suggests it might be appropriate to redefine the

‘day’ and ‘night’ time periods for hospital noise assessment and perhaps consider the addition of an

‘evening’ period.

The measured levels essentially follow some very general patterns, climbing steadily as morning

activity increases on the ward; peaking as lunch is served and then decreasing slightly during the

patient rest period. Levels increase again during the afternoon reflecting additional noise generated

during visiting times, and then begin to decrease after the early evening meal. This ward is large, with

a diverse group of patients; some with severe injuries as a result of road accidents; some with injuries

resulting from elective surgery; others suffering from both physical trauma and a level of dementia.

Due to this diversity very different levels and types of care are required on this ward. This in itself

leads to less well defined routines of patient care and hence more variation in measured noise levels.

This is not necessarily the case in other study wards which deal with more specific types of medical

problems or surgical procedures.

Further analysis of high level noise sources is carried out in the next section.


Average LAeq,1hr levels over 24 hours, as presented in the previous section, provide some general

comparisons and show fluctuations related to ward routines. However, to build up a more detailed


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picture of the sources of high level noise at each location, the numbers of occurrences of LAmax in 5 dB

bands from 70 to 95 dB have been examined. Figures 9.7 and 9.8 show the average number of high

level noise events captured during the day and night in different measurement locations.

It can be seen in Figure 9.7 that apart from the nurse station, which has already been discussed in

some detail in Section 9.4.1, the largest numbers of day time high level noise events are recorded in

the 12-bed bay, closely followed by two bays in the elderly trauma unit. This is interesting as the

average noise level in the 12-bed bay is very similar to that in the other bays, see Table 9.2 and

Figure 9.6. This is a good illustration of why it is necessary to break the data down and fully

understand the content of the noise, rather than relying on overall noise levels.

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85 ≤ LAmax < 90dB

90 ≤ LAmax < 95 dB


The 12-bed bay has a small desk situated in the centre of the ward with several PCs and a telephone.

For logistical purposes the microphone was suspended above this area and thus many of the high

level noise sources captured were related to nurse activity at or around this desk, including

conversation; talking on the telephone; and the use of ring binders. This desk area was open to the

ward and thus any high level sounds captured here would be heard by the patients on the bay. This

area was busiest during the day, however high level noise attributable to administrative tasks was

also captured during the night – a potential disturbance to patients on the bay. Other high noise levels

captured can be attributed to the furniture scraping on the floor; the drinks cup dispenser; the jangling

of crockery and cutlery at meal times; general movement around the ward and conversation at visiting

times. The corridor to the bathroom was situated behind the microphone, and doors banging were

often captured at high levels.


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The 7-bed and 3-bed bays in the elderly trauma unit had many more high level noise events

associated with patients calling out and clinicians talking to patients loudly. This had been expected

by the ward manager. Patients here are often very confused or distressed, and so to try and engage

with, and subsequently comfort the patients, clinicians need to raise their voices.

It can be seen in Figure 9.8 that apart from the nurse station, the largest numbers of night time high

level noise events are recorded in the elderly trauma unit. As many of the patients are woken up

before the designated start of day (07.00), many of the high level sources of noises are related to

distress and confusion during this process, which occurs between 06.30 and 07.00. Although listed as

night time noise, this gives a misleading indication that these bays are noisy throughout the night,

which is not generally the case. The high noise levels during this time are further illustrated by the

noise level trace shown in Figure 9.9, which clearly demonstrates high levels of noise from 06.41 to

07.00, much of which can be attributed to a confused patient crying out and the staff trying to calm

them. The blue line represents the average LAeq,8hr measured in the bay during the night, further

highlighting the high levels of noise shown here.

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75 ≤ LAmax < 80 dB

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85 ≤ LAmax < 90dB



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Figure 9.9 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a 19 minute interval

in the elderly trauma unit

To illustrate the types and noise levels of typical high level events found in the multi-bed bays,



Table 9.4 Examples of noise events in the multi-bed bays


Bed rails 84

Patients crying out 85 - 91

Drinks cup dispenser 78

Shoes squeaking on floor 74

Trolley 73

Medical equipment alarm 71

It can be seen in Table 9.4 that patients crying out are measured at levels from 85 to 91 dB LAmax.

Such high noise levels would undoubtedly cause disturbance to other patients on the bay.

9.4.4. Representative measurement interval

In Chapter 6 it was established that a representative measurement interval was one week in duration

(5 days when the ward occupancy decreased at weekends). It was felt important that this

measurement interval was validated during the main study when it was possible to measure two non-

consecutive weeks’ worth of noise level data in the same bay. Noise level measurements in the 12-

bed male bay were captured for two seven day periods, several weeks apart. Figure 9.10 shows the

averaged LAeq,1hr levels measured during the two measurement periods. It can clearly be seen that the

averaged levels are similar in both level and fluctuation. A χ2 goodness of fit test found no statistically

significant difference between the two datasets at the 1% level.


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159

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Week 1 Week 2

Night time

Day time

Figure 9.10 Average LAeq,1hr levels over 24 hours for two non-consecutive weeks in the 12-bed bay

It can therefore be said that a seven day measurement interval is representative interval for the 12-

bed bay, and reinforces the findings of the pilot study, that one week’s worth of data (5 days when the

ward occupancy decreased at weekends) is a representative measurement interval for the study.


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9.5. Ward N3 (medical)

Ward N3 is situated on the third floor of a new modular wing. It is a respiratory ward for both acute

and chronically sick patients and contains a specialist respiratory unit to care for patients who require

non-invasive respiratory ventilation. The ward has a total of 25 beds divided between nine single

rooms; two 4-bed bays (one male and one female); and a respiratory care unit which contains two

adjoining 4-bed bays (one male and one female).

The ward generally runs at 100% occupancy. Weekends may be slightly quieter as there are no

routine tests carried out, but occupancy levels remain the same.


Completed in 2009, this modular block is of mainly timber construction, double glazed with both

mechanical and natural ventilation. Built to comply with acoustic standard HTM 2045, the suspended

ceiling grid is fitted with Ecophon acoustic tiles with good absorption properties; the plasterboard stud

walls are sound insulated with 50 mm of mineral wool in the cavity; and the floor is heavy duty vinyl on

flooring grade ply, again well insulated in the void.

Interestingly, staff working on this ward have found that the floor (which is timber and a little springy)

has had a detrimental effect on their feet. The design of the ward, which is ‘L’ shaped, also makes the

staff cover quite large distances each day, potentially adding to this detrimental effect. Complaints

regarding the floor were so widespread that remedial work has been carried out to stiffen the floor

slightly since it was first constructed. Feedback from staff suggests that this is generally felt to be an

improvement.

The Estates team were particularly interested to see whether this particular building, which is of

untypical construction, suffered from any unusual noise problems. It was not envisaged that these

would be related to sound attenuation, but it was considered that the floor construction could

potentially magnify certain sounds.

9.5.2. Ward Layout

As can be seen in Figure 9.11 on page , the ward is ‘L’ shaped with patient accommodation, staff

offices and healthcare utilities on both sides of a long central corridor. The entrance to the ward is at

the top of the ‘L’, with the patient multi-bed bays situated on the longer section of corridor and the

single rooms on the shorter section. The siting of the single rooms in this way potentially means less

traffic flow in the corridor, as apart from a store at the very end of the ward, there is no reason to walk

past the single rooms unless going to see a patient. All patient accommodation has full ensuite

bathroom facilities.

The nurse station is centrally located at the corridor intersection. It is opposite the 4-bed female bay,

the clean and dirty utility rooms and storeroom, with a drug preparation room behind. It may be a


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source of noise to the female patients in the opposite bay, as not only is the nurse station itself busy,

but staff are constantly opening and closing the doors to the utility rooms and store. The other staff

administrative areas are situated close to the ward entrance, with the ward clerk’s desk area, seminar

room and general offices based here. The respiratory care unit which contains two adjoining single

sex 4-bed bays has its own nurse station.


Doors

Doors to the 4-bed bays and single rooms are kept open at all times, except if a patient is infectious

and requires barrier nursing (this applies to single rooms only).

The doors to the respiratory care unit are shut at night as this ward is perceived as quite noisy due to

the amount of equipment in use. This unit has its own dedicated nurse station, which enables the

doors to be closed.


Staffing levels are highest on the day shift, from 07.15 to 19.15, with eight nursing staff present. This

reduces to five nursing staff for the night shift which lasts from 19.15 to 07.15. Other staff members

start work at 08.30, and include a ward clerk; four physiotherapists; two occupational therapists; and

four other assistants who are either pharmacists or are involved in collecting bloods. There are eight

doctors serving this ward, with the doctors’ rounds generally beginning around 10.00 and continuing

into mid- afternoon. Four domestic staff also work on the ward, cleaning and serving meals and drinks

During weekends there are slightly fewer staff with six staff nurses and one healthcare assistant.

Ward routines

The first patient visits by clinicians occur at around 06.00 for general observation; however, general

activity on the ward does not begin until 07.15 when the main lights are switched on. The morning

shift handover also takes place at this time and is carried out at the bedside, where there are

generally three members of staff present.

At 08.00 the first drug round begins and staff begin to get patients up ready for breakfast. The majority

of patients are bed bound, so staff will sit them up, sorting out toileting and so on. Following breakfast,

patients are washed and beds are changed. Beds are often moved around at this time in readiness

for admissions and discharges.

Doctors begin ward rounds at around 10.00; these continue throughout the morning and into mid

afternoon.

Drug rounds and patient observations continue throughout the day at noon, 17.30 and 21.00.


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The night shift changeover takes place at 19.15, and, as with the morning shift, a handover takes

place at the bedside. This is followed by patient observations and staff settling patients down for the

night. The ward lights are finally dimmed at around 22.30.

Meal times

A cold breakfast is served by the ward domestic staff at 08.30, followed by a separate hot drinks

trolley.

Lunch is served at midday, with the food arriving on a heated trolley and subsequently plated up in

the ward corridor, next to the nurse station. Meals are taken round to patients on a smaller trolley and

are served by the ward domestic staff. This is followed by a separate hot drinks trolley.

Afternoon hot drinks are served at 15.00, followed by the evening meal and hot drinks at 18.00.

Visiting times

Visiting times are strictly adhered to in this ward, except for terminally ill patients. Visiting time is split

to allow patients to eat their evening meal without disturbance. The hours are from 14.30 until 17.00,

and 19.00 until 20.30.


The following were considered to be the main sources of noise:

Daily facilitator meeting

This meeting is held each day at 09.15 by the shift co-ordinator at the ward scheduling board next to

the nurse station. All staff attend this meeting which generally lasts for 30 minutes. This is a potential

source of noise to those female patients in the opposite 4-bed bay.

Nurse station

Noise levels at the nurse station are felt to be high, with one staff member commenting that there are

often multiple conversations taking place and that it is sometimes difficult to hear what is being said

on the telephone.

Telephone

There are two telephones at the nurse station. The ward manager feels that they ring incessantly,

especially during the morning.

Doorbell

This is answered by the ward clerk during working hours; otherwise it is answered by the nursing staff

at the nurse station.


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163

Patientline

This system is available here at a cost. Headphones are provided but are often not used.

Mobile phones

The ward manager considers the phone charges levied by ‘Patientline’ to be exorbitant and is

therefore lenient towards the use of mobile phones on the ward.

Equipment

Due to the nature of patient care on this ward, there are a number of pieces of medical equipment that

are in use. Ventilators, pumps and vital signs equipment are all common here.

Nurse call & emergency call

These systems are set on the night time level at all times, and are felt to be ineffectual in terms of

design.

The ward manager feels that the nurse call system on the ward is poorly designed, as busy staff are

often unaware that it has been activated. For example, if a patient in 4-bed bay A presses the nurse

call bell, a tone is emitted in this bay, with the occurrence shown on a display panel in this bay and at

the nurse station. A light is also displayed outside the bay in the corridor. However, this occurrence is

not shown on the display panels in any other patient accommodation, so if nursing staff are all busy

out on the ward, they are not necessarily aware that the nurse call has been pressed. The ward

manager feels that all occurrences of nurse call should be shown on all screens in all bays.

Each time the nurse call is activated, a tone is emitted in the ward manager’s office, which cannot be

cancelled or changed in volume. This is extremely annoying to the ward manager who finds that the

nurse call constantly sounding has a negative impact on her work. As the person responsible for

overseeing the running of the entire ward, she does not consider it necessary to hear every

occurrence of the nurse call, preferring instead to only be able to hear the emergency call bell, which

signifies a more serious event. The ward manager also commented that the emergency call bell was

ineffectual as it could not be heard throughout the ward and considered that a remote paging system

or similar would be preferable to the current systems.


The ward manager was supportive of the study and spent time ensuring that ward routines and

systems were understood. There were no undue concerns regarding the cleaning of the equipment

and the proposed microphone positions were acceptable. For comparison purposes it was considered

important that the microphone was placed in similar locations in each accommodation type. The

microphone positions are shown on the ward plan in Figure 9.11.


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164

As in previous locations, a 300 mm ceiling bracket was used to suspend the microphone from the

ceiling grid. The environmental case housing the SLM was positioned so as to minimise the risk of

theft and its impact on staff duties and patient care. In the patient bays the case was placed under a

section of worktop, and in the single rooms it was positioned behind an easy chair.

The distribution of patient questionnaires was not as straight forward as in previous study wards.

Patients who were bed bound and suffering from respiratory conditions were not considered to be fit

enough to complete the questionnaire. Only those patients who were able to get up and walk down to

the day room would be approached by the ward clerk (whose desk was opposite this room). This

meant that the number of patient questionnaires completed during the study period was low (n=13).

Laminated posters were displayed throughout the ward common areas explaining the study, and it

was hoped that staff would be informed of the research during staff meetings. Unfortunately, this was

not the case, and many of the staff approached during the study period had no knowledge of the work

being carried out. Questionnaires were left for completion in the staff room, however only a relatively

small amount were completed by the staff (n=10).

Figure 9.11 Detailed plan of the ward N3 showing microphone positions


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9.6. Overall acoustic survey results Ward N3



Table 9.5 Measurement location, time interval and patient type


Nurse Station 5 days N/A


4-bed bay B 8 days Female (special care)

4-bed bay C 7 days Female

Single room J 7 days Male / Female

Single room K 9 days Male / Female



Table 9.6 Average LAeq measured for 24 hour, day and night time periods at each location.




Nurse Station 51.7 53.4 47.4

4-Bed Bay A 50.9 52.3 44.6

4-Bed Bay B 52.1 53.3 47.2

4-Bed Bay C 48.8 50.0 44.3

Single Room J 49.3 50.6 43.6

Single Room K 51.1 52.5 45.1


in Figure 9.12 for clarity. As with the wards at Bedford Hospital, noise levels in all patient

accommodation exceed those suggested in the WHO guidelines. It can also be seen that all average

day and night time levels measured in the patient accommodation were very similar, within a 3.3 dB

range from 50.0 to 53.3 dB LAeq, 16hr during the day and 3.6 dB range from 43.6 to 47.2 dB LAeq, 8hr at

night. Interestingly, the nurse station on this ward has comparable noise levels to those shown in most

of the patient accommodation.


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167

The day to night drop in levels is fairly consistent, with an average drop of 7 dB in the patient

accommodation and a smaller drop of 5 dB at the nurse station. This is comparable with nurse

stations on the study wards at Bedford Hospital and Ward D8.

The highest day and night time levels were measured in 4-bed bay B, the special respiratory care

unit. This is unsurprising given the amount of respiratory equipment in use on this bay.

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results from the multi-bed bays shown in Section 9.6.2 and levels measured in the single rooms in

Section 9.6.3.


Figure 9.13 shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours for the nurse station. The

figure shows that noise levels are very steady during the night, from around 21.30 until 05.00, after

which they climb to a temporary peak during the daily facilitator meeting at around 09.30. Other small

peaks can be observed at lunch time, dinner time and during evening shift changeover. The

measured LA90,1hr levels provide a good indication of the variation in background noise levels over

time, with night time background levels remaining very constant at around 39 dB LA90, and day time

background levels peaking at lunch time at around 45 dB LA90.


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168

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Nurse station LAeq Nurse station LA90

Night time

Day time


To illustrate the fluctuating nature of noise in the short term, Figure 9.14 shows noise levels captured

at the nurse station over a 13 minute time interval during the afternoon, with the microphone

approximately 2 m away from the main desk area. Certain high level noise events with LAmax greater

than 70 dB have been identified.

Figure 9.14 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a 13 minute interval at the

nurse station during the afternoon

A number of rooms are situated close to the nurse station, including the clean and dirty utility rooms,

and a storeroom. All doors to these areas have security access via a key code pad. Staff often have

their hands full when entering or leaving these rooms, and so the doors to these rooms are generally

left on the latch, avoiding the need to input the security code and making the doors easier to push

open. Unfortunately, this has the adverse effect that the door literally bounces when it shuts, causing

a loud noise. This is a good example of the ward not being used as its designer intended and is

RING

BINDERS BANGING DOORS

BANGING DOOR


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169

further illustrated by Figure 9.15, which shows the 1/3 octave band frequency spectrum of a typical

door bang. Banging doors accounted for 48% of the total number trigger files captured during the

measurement period in this location.

The acoustic ceiling tiles installed throughout the ward are optimal at speech frequencies. The

frequency content of the banging door shown in Figure 9.15 is clearly biased towards low frequencies.

This is a good illustration of the type of high level noise for which current levels of absorbency may

not be so effective.

Figure 9.15 Frequency content of door bang at the nurse station

As in other study wards, the use of ring binders also caused a relatively high number of trigger files at

the nurse station (8% of the total number captured during the measurement period). All patient

records are kept in ring binders, along with other reference materials, and often are the main source

of late night noise, when the staff are catching up with administrative work.






Doors banging 77; 79

Ring binder 72

Trolley 77

Footsteps 71

Unusually, footsteps are a source of high level noise at the nurse station. This is caused by groups of

people walking past the microphone, and not a single person, which would not be sufficiently loud.

However, the fact that footfall is responsible for noise levels exceeding 70 dB LAmax indicates a

potential issue with the timber floor and its vinyl covering. This is confirmed by the questionnaire

responses in which 40% of ward staff found the sound of footsteps annoying, and 20% of patients


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cited footsteps as a cause of night time disturbance. These percentages are the highest found in

relation to annoyance and disturbance from footsteps on any study ward.

Unlike other study wards the internal telephone, nurse call and doorbell were not set at levels which

were loud enough to create trigger files at the nurse station, however this did not prevent these

systems from causing annoyance and interference to staff, as can be seen in Section 9.9, and

suggests that noise annoyance is not related to noise level alone.


Figure 9.16 shows the averaged LAeq,1hr levels over 24 hours for the three 4-bed bays and the average

background level (LA90,1hr) of all bays. It can be seen that the levels measured in the male and female

bay are reasonably consistent, with the male bay appearing slightly noisier during the day and the

female bay slightly noisier at night. Measured levels in the special respiratory care unit are

consistently higher than in the other two bays. The reasons for this are investigated further in Section

9.6.4. The average background level varies from around 38 dB LA90 during the night to 42 dB LA90

during the day; these levels are slightly lower than those measured at the nurse station.

Levels appear to follow ward routines to some degree, with the levels rising steadily after the main

lights are switched on just after 07.00, and temporarily peaking at the end of the staff daily meeting,

when nursing staff and doctors return to the wards for the ward rounds. Levels peak again around

lunch time. After lunch levels in the respiratory care unit remain fairly stable until around 23.00, but

levels in bays A and C can be seen to fluctuate slightly more, with a peak around 18.30 in bay A. This

may be related to the serving of the evening meal.

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4 Bed Bay A (Male) 4 Bed Bay B (Special Respiratory Care) 4 Bed Bay C (Female) Average LA90

Night time Day time

WHO GUIDELINES

Figure 9.16 Average LAeq,1hr for each multi-bed bay and combined average LA90,1hr level for all bays

over 24 hours


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171

Figure 9.16 also shows that the WHO day / night division is not a particularly good fit. Noise levels


is served. This suggests it might be appropriate to redefine the ‘day’ and ‘night’ time periods for

hospital noise assessment.



average level from the three multi-bed bays is also shown for comparison purposes. It can be seen

that levels for single room J are consistently lower than the average of the multi-bed bays, and noise

levels measured in single room K are similar to the multi-bed average. It is also noticeable that the

effects of the ward routines on the measured levels appear to be much less pronounced in the single

rooms.

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Single Room J Single Room K Mean 4-Bed Bays

Night time Day time

WHO GUIDELINES

Figure 9.17 Average LAeq,1hr levels over 24 hours for the single rooms

The day time measured LAeq,16hr for single room J is lower than for any other single room measured in

any of the study wards. This was in part due to the patient, who was elderly, unable to speak well due

to his respiratory problems, slept a great deal and received few visitors. In this instance, patient

procedures accounted for the highest percentage of high level noise events, including doctor’s visits,

nurses’ observations, and patient washing and changing. This patient was bedridden and so required

a high level of care. Medical equipment alarms, when they were activated, were typically no louder

than 57 dB LAmax.


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172

The occupant of single room K had a very bad cough, but was well enough to talk to staff and

received more visitors than the patient in room J. High level coughing, clinical activity and

conversation accounted for the higher noise levels in this single room.



occurrences of LAmax in 5dB bands from 70 to 95 dB have been examined. Figures 9.18 and 9.19



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75 ≤ LAmax < 80 dB

80 ≤ LAmax < 85dB

85 ≤ LAmax < 90dB


It can be seen that 4-bed bays A and B show the largest numbers of high level noise events during

the day, with 4-bed bay C registering much fewer. This highlights the limitations of simply viewing the

average LAeq,1hr levels, as shown in Section 9.6.2, which indicates similar levels between bays A and

C. The average number of day time high level noise events with an LAmax between 70 and 75 dB in

bay A is 100 higher than in bay C, suggesting some differences in the noise climate.

To explain some of the differences between bays in terms of high level noise, it was found that the

nurse call was responsible for 20% of trigger files captured during the seven day measurement period

in bay A, with each intermittent tone captured at an average level of 72 dB LAmax. However this was not

the case in bays B and C as here the nurse call did not generate any trigger files, only registering at

around 51 dB LAmax. Much of the high level noise generated in bay B fell into the ‘unidentifiable’

category, suggesting more clinical activity in this bay. Conversation and administrative tasks at the

integral nurse station also added to these noise sources.


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173

It can also be seen in Figure 9.18 that, unusually, the nurse station has more high level noise events

with LAmax between 75 and 80 dB, than those with LAmax between 70 and 75 dB. As discussed in

Section 9.6.1, this is largely due to the banging doors, which are measured at consistent levels in this

range.

Figure 9.19 shows the night time average number of high level noise events recorded at each location.

In this case it is the nurse station and bay B which show the highest numbers of events. As with the

day time noise, the nurse station is affected by doors banging, and other sources of high level noise

are mostly generated by administrative activity, especially the use of ring binders.

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75 ≤ LAmax < 80 dB

80 ≤ LAmax < 85dB

85 ≤ LAmax < 90dB


As discussed previously, bay B also has its own integral nurse station, and it is this area where some

of the high level noise was generated. Figure 9.20 shows a further breakdown of night time noise in

bay B. It can be seen that patients coughing / sneezing / gurgling and groaning accounts for 45%

percentage of trigger files captured during the night. This is unsurprising as patients in this bay have

acute respiratory problems. Noise due to administrative tasks carried out at the integral nurse desk

accounts for 35% of trigger files; which suggests that patients may be disturbed by activity in this area

during the night.

0 5 10 15 20 25 30 35 40 45 50

Unidentifiable

Cough / sneeze / gurgling / groaning

Furniture scraping

Ring binder / admin at nurses' desk

Cupboard door / drawers

Bathroom door

% of high level noise sources (LAmax > 70 dB)

Figure 9.20 Percentage break down of high level noise events by type in 4-bed bay B


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174

9.7. Ward M4 (surgical)

The Addenbrooke’s Treatment Centre (ATC) was opened in November 2007 at a cost of £84 million.

This building was built under the PFI (Private Finance Initiative) scheme and houses operating

theatres and wards for emergency surgery, a new endoscopy suite, and facilities for all inpatient

gynaecology, urology and breast surgery services. Ward M4 is situated on the 4th

floor of the ATC and

is a surgical ward specialising in urology. The ward has a total of 32 beds, divided between five 4-bed

bays and 12 single rooms, and is predominantly male. Women admitted for treatment on this ward

tend to be put into a single room. 60% of admissions are elective (through a GP) and 40% of

admissions are emergencies. Ward admissions can be at any time during the day and night, with 60%

of patients arriving on the ward on the day of their procedure.

9.7.1. Building construction

The construction of the ATC building is primarily concrete, double glazed and mechanically ventilated.

Built to comply with acoustic standard HTM 2045, the suspended ceiling grid is fitted with acoustic

tiles with good absorption properties; the plasterboard stud walls are sound insulated; and the 1 m

thick reinforced concrete floor is covered with heavy duty vinyl.

9.7.2. Ward layout

A number of senior staff offices and meeting rooms are positioned just before the ward entrance,

which requires card access. The ward is laid out on both sides of a long straight corridor, with the

patient accommodation located on the outer wall of the building, making best use of the natural light

and views over the countryside. All patient rooms have ensuite bathroom facilities. Healthcare utilities

are situated in the centre of the building (on the left of the corridor when walking from the entrance).

Some of these utilities, for example the clean and dirty utility rooms, larger storerooms, larger offices,

and the lifts used for patient transport, are shared with another ward which runs parallel to M4, as

shown in Figure 9.21 on page 179.

There are three nurse stations on the ward, one at the entrance, one halfway down the ward and one

at the end of the corridor. The ward manager felt that the central nurse station and the one closest to

the entrance were likely to be the noisiest, and so for this reason these areas were chosen for

measurement.

The ward is designed so that single rooms are positioned in pairs, and due to the location of the

ensuite facilities, the rooms are set back, allowing patients in these rooms to be further away from

well trafficked corridor areas. This can be seen in Figures 9.21 and 9.22 on pages 179 and 180

respectively. The 4-bed bays open directly out onto the main corridor.

The ward corridors and patient accommodation have a spacious and uncluttered feel, and as

discussed in Section 9.3.1, the ward area is large (1250 m2

with 28 patients) compared to ward D8


___________________________________________________________________________________________________________________

175

(850 m2 with 35 patients). Single rooms have a floor area of approx 18 m

2 and 4-bed bays have a

floor area of approx 53 m2.


Doors

The ward manager prefers all doors to patient accommodation to be left open at all times to allow the

nursing staff to monitor the patients. If a patient falls or gets into difficulties the nursing staff can either

see or hear. Even in rooms where patient barrier nursing is required, doors are still left open. In

general, the only exception is when a patient is nearly fully recovered and waiting to go home.

MRSA

All patients are swabbed for MRSA on admittance and if the results are positive they are generally

placed in a single room. Prior to the swab result being received, the patients are placed in a room with

others whose results are not yet known. Patients are often moved to different locations on the ward

during their stay.

Occupancy levels

During the week the ward runs at 100% occupancy. During the weekend (from Friday evening until

Sunday evening) five beds should be closed, however, it appears that this is a rare occurrence. Bay

23 is always fully occupied as this is closest to the nurse station and therefore is good from an

observation point of view.


Staffing levels from 07.15 until 19.15 are the highest, with seven staff nurses and three healthcare

assistants. This reduces to six nursing staff during the night shift, from 19.15 until 07.15. Other staff

include three cleaners, two ward assistants and a ward clerk. During weekends there are slightly

fewer staff with six staff nurses and one healthcare assistant.

Ward routines

The first patient visits begin at 06.00 for general observations, including temperature, bloods and

urine samples. New admissions begin to arrive on the ward at 07.00.

Morning shift handover takes place in the seminar room between 07.15 and 07.45 and is immediately

followed by a drug round.

The first theatre admissions begin at 08.00, with two sets of porters collecting and returning patients

to and from theatre. This continues throughout the day. At this time there is a great deal of noise at

the nurse station with doctors checking the admissions board and bed managers arriving on the ward.

Doctors begin their ward rounds at this time.


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176

At 10.30 the phlebotomists arrive on the ward with two trolleys to collect bloods, this is followed by

further drug rounds and general observations which are carried out at 12.30, 17.00 and 21.00.

Doctors pay post-operative visits to patients at 18.00 and the night shift handover takes place

following this, between 19.15 and 19.45 in the seminar room.

The main ward lights are turned out at 22.30.

Meal times

Breakfast and coffee is served by ward assistants on trolleys between 07.45 and 08.30. This is

followed by a mid morning tea round at 10.00.

Lunch is served at 12.00, followed by a tea round, with food delivered to the ward in a large ‘hot’

trolley. Meals are plated up and taken to the patients by hand by two ward assistants and a

healthcare assistant. Unlike Bedford Hospital, mealtimes are not ‘protected’ on this ward and patients

may still be undergoing CT scans or being taken to and from surgery during the serving of meals.

There is a further tea round at 15.00, followed by a light supper at 17.00. The final tea round is at

20.00.

Deliveries

Fresh linen is delivered to the ward on a daily basis, at 09.00. The linen is delivered in a large cage

which is taken from the lift lobby to the central nurse station and swapped for the dirty linen trolley.

Thursday is the main day for ward deliveries, with items brought up to the ward in large cages after

lunch.

Visiting times

The official hours for visiting time are 14.00 until 20.00.


The following are thought to be the main sources of noise:

Doorbell

The entrance to the ward is through a security door, which has a doorbell, the use of which peaks

during visiting time.

Cleaning

Cleaning begins in the morning and continues throughout the day and comprises of dusting and

mopping the floor. Full floor buffing takes place on a weekly basis. Bins are changed twice daily (more

if required).


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177

Doors

Fire doors are heavy and tend to slam loudly.

Nurse Call

Telephone

There are 3 telephones on the ward. The ward manager felt that during busy times the phones ring

endlessly as there is no member of staff free to answer them. A cordless phone was tried as an

alternative, but this was not entirely successful and was eventually lost.

Patientline

This system is available here at a cost. Headphones are provided but are not always used.

Portable DVD players

Patients sometimes bring these in to watch their own DVDs.

Mobile Phones

To avoid setting a precedent, even the doctors tend to go out into the hallway to use their mobile

phones.


The ward manager was supportive of the study and spent time ensuring that ward routines were

understood. Particular interest was expressed in measuring noise levels at two of the nurse stations

for comparison purposes, as it was suspected that the central station was adversely affected by noise

from the nearby lifts, and had become a congregation point for staff. Both areas were incorporated

into the study.

Two four bed bays and two single patient rooms were identified as suitable study locations with input

from the ward manager. For each accommodation type, similar positions were found for the

microphone, which was suspended from the ceiling grid using a 300 mm ceiling bracket. The

environmental case housing the SLM was positioned so as to minimise the risk of theft and its impact

on staff duties and patient care. In the patient bays the case was placed on a section of worktop, and

in the single rooms it was positioned behind an easy chair. A ward plan showing these positions can

be seen in Figures 9.21 and 9.22.

Although the ward clerk was tasked with passing the questionnaires to patients who had been on the

ward for over 24 hours and were deemed fit enough to complete the questionnaire, this was not as

successful as in other study wards. The role of ward clerk rotated between a number of staff and so

the questionnaires were often forgotten; with only 14 completed questionnaires collected.


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178

Laminated posters were displayed throughout the ward common areas explaining the study, and it

was hoped that staff would be informed of the research during staff meetings. Unfortunately, this was

not the case, and many of the staff approached during the study period had no knowledge of the work

being carried out. Questionnaires were left for completion at the nurse station, and a box was

provided for completed questionnaires, however only a relatively small number (10) were completed

by the staff.

Figure 9.21 Plan of Ward M4 detailing shared areas and microphone positions

Figure 9.22 Detailed plan of Ward M4 showing study locations and microphone positions


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181

9.8. Overall acoustic survey results Ward M4



Table 9.8 Measurement location, time interval and patient gender


Nurse station 1 5 days N/A

Nurse station 2 7 days N/A


4-bed bay B 8 days Male

Single room A 7 days Female

Single room B 9 days Male / Female







Nurse Station 1 56.4 55.1 48.1

Nurse Station 2 52.2 53.6 46.7

4-Bed Bay A 50.6 52.7 43.0

4-Bed Bay B 52.4 54.0 43.4

Single Room A 50.9 52.3 42.1

Single Room B 53.2 53.5 49.1


in Figure 9.23 for clarity. As with the wards at Bedford Hospital, noise levels in all patient

accommodation exceed those suggested in the WHO guidelines without exception. It can also be

seen that all average day time levels measured in the patient accommodation were very similar,

within a 1.7 dB range from 52.3 to 54.0 dB LAeq, 16hr. Night time levels were also very consistent with a

1.3 dB range from 42.1to 43.4 dB LAeq, 8hr, with the exception of single room B which had a much

higher average of 49.1 dB LAeq, 8hr . Day to night drop was also fairly consistent with an average drop of

10.2 dB in patient accommodation, with the exception of single room B which had an average drop of

just 4.4 dB.


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182

As the ward manager suspected, noise levels were higher at the central nurse station (nurse station

1), however the differences between the nurse stations were very small, with a 1.5 dB difference in

average levels during the day and 1.4 dB difference at night. Further analysis is necessary to

understand the level fluctuations and sources of high level noise in these two cases, which are

discussed in Sections 9.8.1 and 9.8.4. Results from the multi-bed bays and single rooms are

presented in Sections 9.8.2 and 9.8.3 respectively.

0

10

20

30

40

50

60

70

Nurse Station 1 Nurse Station 2 4-Bed Bay A 4-Bed Bay B Single Room A Single Room B

So

un

d P

ressu

re (

dB

A)

Day

Night



Figure 9.24, shows the averaged LAeq,1hr and LA90,1hr levels over 24 hours for the two nurse stations.

The figure shows that noise levels at Nurse Station 1 (NS1) are consistently higher than those

measured at Nurse Station 2 (NS2) during the day and then converge at around 21.00 for four hours.

Levels at NS2 are again consistently lower from 01.00 until 05.00, suggesting less activity in the area

at this time.

Average levels at NS1 show several peaks in line with the ward routines. Levels rise to an initial high

at around 08.00, when the doctors and bed managers arrive at the nurse station to check the day’s

schedules. Another peak can be seen around lunch time and then, as suspected by the ward

manager there is a peak at the end of the day shift.

Background levels during the night are around 37 LA90,8hr, and provide a good indication of the overall

building services noise.


___________________________________________________________________________________________________________________

183

20

30

40

50

60

70

So

un

d P

ressu

re (

LA

eq

,1h

r)

Time (24h:00)

LAeq Nurse Station 1 LAeq Nurse Station 2 LA90 Nurse Station 1 LA90 Nurse Station 2

Night timeDay time

Figure 9.24 Average LAeq,1hr and LA90,1hr levels over 24 hours at the nurse stations

Figure 9.25 shows noise levels captured at NS2 over a 15 minute time interval at 05.30 in the

morning, with the microphone approximately 2 m away from the main desk area. Using the trigger

files captured when LAmax exceeds 70 dB, certain high level noise events have been identified.

Figure 9.25 LAmax,2s (green trace) and LAeq,2s (red trace) fluctuating over a 15 minute interval at the

nurse station at 05.30

The door to the dirty utility room is situated behind NS2 and each time the door closes it generates a

noise with an LAmax of 72 dB. This room is used a great deal and is responsible for many trigger files,

both day and night. Other sources of night time noise at this nurse station are generally related to

administrative tasks and include ring binders, and desk drawers banging shut. High level noise events

during the day are similar, with more high level conversation and noise from corridor traffic, such as

trolleys.

BANGING DESK

DRAWERS

CLOSING DOOR CLOSING DOORS


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184

High level noise events captured at NS1 are generated in the main by high levels of conversation.

This nurse station is larger than NS2 and many more staff congregate here. As with NS2,

administrative tasks are also responsible for some high level noise events, with a ring binder captured

at 83 dB LAmax. Interestingly, although the nurse call, doorbell and internal telephone are all cited by

staff in this ward as annoying and interfering with their ability to carry out their jobs effectively (see

Section 9.9.1), none of these systems is loud enough to generate high level noise events, that is LAmax

greater than 70 dB.


Figure 9.26 shows the averaged LAeq,1hr and background levels (LA90,1hr) levels over 24 hours for the

two 4-bed bays. It can be seen that the levels measured in bays A and B are reasonably consistent,

with bay B appearing slightly noisier during the main part of the day. The average background level in

bay B is consistently lower at night, at around 32 dB LA90, with bay A around 35 dB LA90. An

explanation for these differing levels could be the proximity of the main nurse station. Bay A is

opposite the ward lifts and close to NS1, whereas bay B is opposite an aided bathroom and store,

which would be little used at night. As discussed previously doors to the multi-bed bays are left open

at all times, and thus noise from the ward lifts and NS1 may affect background levels.

20

30

40

50

60

70

So

un

d P

ressu

re (

LA

eq

,1h

r)

Time (24h:00)

LAeq 4-Bed Bay A LAeq 4-Bed Bay B LA90 4-Bed Bay A LA90 4-Bed Bay B

Night time Day time

WHO GUIDELINES

Figure 9.26 Average LAeq,1hr and LA90,1hr level for each multi-bed bay over 24 hours

Levels appear to follow ward routines to some degree, with the levels rising steadily at around 06.00,

when the first observation round begins. At around 08.00, when the doctors arrive on the ward and

theatre admissions begin, levels increase sharply. A small dip can be seen just before the start of

visiting time, with levels decreasing slowly after the evening meal is served.


___________________________________________________________________________________________________________________

185

Figure 9.26 also shows that the WHO day / night division is not a particularly good fit. As discussed,

noise levels increase steadily from around 06.00 rather than 07.00, and begin to decrease after the

evening meal is served. This suggests it might be appropriate to redefine the ‘day’ and ‘night’ time

periods for hospital noise assessment.

The microphone situated in the multi-bed bays was suspended from the ceiling in the corner of the

room close to the entrance doors. In both bays this was over a small worktop area, where there was

also a rubbish bin, plastic apron and glove dispenser, sink and some hospital wheeled equipment

stored. To avoid any coloration of results due to the use of the sink and bin, this location was chosen

in both bays, to allow for comparisons. Further discussion of high level noise can be found in Section

9.8.4.



average level from the two multi-bed bays is also shown for comparison purposes. It can be seen that

at night, levels for single room A are consistently lower than the average level of the multi bed bays

and levels for single room B are consistently higher than this average. During the day all levels are

comparable, following similar patterns of fluctuation

20

30

40

50

60

70

So

un

d P

ressu

re (

LA

eq

,1h

r)

Time (24h:00)

LAeq Single Room A LAeq Single Room B Mean LAeq 4-Bed Bays LA90 Single Room A LA90 Single Room B

Night time Day time

Figure 9.27 Average LAeq,1hr and LA90,1hr levels over 24 hours for the single rooms

Single room A is situated opposite the main nurse station; the internal phone ringing and staff talking

loudly and laughing can often be heard in the background when reviewing trigger files of high level

noise events inside this room. However, it is assumed that the door to this room is shut at night,


___________________________________________________________________________________________________________________

186

resulting in the extremely low background noise levels measured, at around 24 dB LA90. These are the

lowest background levels measured in any study ward.

During the measurement period there were three different patients occupying single room A. All were

female, and relatively quiet. Sources of high level noise were routinely caused by room cleaning, bin

bag changing and use of the rubbish bin, which was captured at a level of 81 dB LAmax. Visits by

clinicians and the serving of meals also accounted for a percentage of high level noise, with domestic

staff talking to the patients unnecessarily loudly at times.

The patients in single room B during the measurement period were male, with sources of high level

noise found to be similar to those in room A. Additional high level events were the closing of the room

door, measured at around 78 dB LAmax, and persistent coughing of the second patient staying in the

room at levels up to 79 dB LAmax. Night time LAeq levels in this room were on average 7 dB higher than

those measured in single room A, with background levels around 13 dB higher. It is thought this was

due to the constant use of a portable cooling fan and some low level alarms of the monitoring

equipment in this room.


To help build up a wider picture of the sources of high level noise at each location, the numbers of




It can be seen that the main nurse station (NS1) accounts for the majority of high level noise events,

with an average of over 450 events during the day between 70 and 75 dB LAmax. As already

discussed, much of this is due to high level conversation between staff, and some administrative

tasks. Much of the high level noise at NS2 is due to the banging shut of the door to the dirty utility

room; the effect of this which may be to build up an artificially high picture of noise levels in this area.

4-bed bay B shows the largest numbers of high level noise events measured in a multi-bed bay during

the day, with 4-bed bay A registering much fewer. Here, the specific difference appears to be primarily

due to a patient with a loud and persistent cough in bay B. All other high level events are similar, with

the use of the rubbish bin, plastic apron and glove dispenser and sink noticeable in both bays. A loud

bang is consistently captured as the lid of the rubbish bin lid closes, measured at an average level of

83 dB LAmax. With the nearest patient in a bed only a short distance away from this bin, this may cause

annoyance. Although not loud enough to create a trigger file, music can sometimes be heard in the

background of trigger files captured in the bays. This is substantiated by a patient comment made

regarding the use of radios and TVs without enforcing the use of headphones.


___________________________________________________________________________________________________________________

187

0

50

100

150

200

250

300

350

400

450

500

Nu

mb

er

of

reco

rde

d n

ois

e e

ven

ts b

y ca

teg

ory

70 ≤ LAmax < 75 dB

75 ≤ LAmax < 80 dB

80 ≤ LAmax < 85dB

85 ≤ LAmax < 90dB

90 ≤ LAmax < 95 dB


Figure 9.29 shows the night time average number of high level noise events recorded at each location.

In this case it is NS2, NS1 and single room B respectively which show the highest numbers of events.

As with the day time noise, NS2 is affected by the door of the dirty utility room banging, whereas the

majority of high level noise at NS1 is caused by high levels of conversation and administrative tasks.

As discussed previously, there was a patient in single room B with a loud, persistent cough that

accounts for the numbers of high level noise sources captured during the night.

0

10

20

30

40

50

Nu

mb

er

of

reco

rde

d n

ois

e e

ven

ts b

y ca

teg

ory

70 ≤ LAmax < 75 dB

75 ≤ LAmax < 80 dB

80 ≤ LAmax < 85dB

85 ≤ LAmax < 90dB



___________________________________________________________________________________________________________________

188


The design of the questionnaire surveys was discussed in detail in Section 5.4.

Staff response was good in Ward D8 with 21 questionnaires completed, but response rate in the other

wards was low, with only 10 staff completing the survey in wards N3 and M4.

The following sections discuss results from the staff questionnaires and examine the differences

between perceptions on the three wards.



of all the respondents, 73% were female and 27% male, with similar percentages in all three wards.

Figure 9.30 shows the ages of the respondents. It can be seen that in all wards the respondents were

generally younger than 50, with a higher percentage of young staff members completing the

questionnaire in wards D8 and N3.

0 20 40 60 80 100

Less than 20

20-30

31-40

41-50

51-60

60+

Percentage of respondents

Ag

e b

an

d (

ye

ars

)

D8 (n=21)

N3 (n=10)

M4 (n=10)

Figure 9.30 Age of respondents by band

The length of time worked both on the wards and at the hospital are shown in Figures 9.31 and 9.32

respectively, which suggest that many of the staff have worked at the hospital for longer than they

have worked on their specific ward.


___________________________________________________________________________________________________________________

189

0 10 20 30 40 50 60 70

< 1 year

1- 2 years

2 - 3 years

3-4 years

4-5 years

5+ years


Tim

e w

ork

ed

on

th

e w

ard D8 (n=21)

N3 (n=10)

M4 (n=10)

0 10 20 30 40 50

< 1 year

1- 2 years

2 - 3 years

3-4 years

4-5 years

5+ years


Tim

e w

ork

ed

at

the

ho

spit

al

D8 (n=21)

N3 (n=10)

M4 (n=10)

Figure 9.31 Time worked on the ward Figure 9.32 Time worked at the hospital



annoyed by noise. Figure 9.33 shows that the highest percentages of staff on all wards were ‘slightly’

annoyed by noise. Ward D8 shows the most diverse response, with some staff indicating ‘not at all’

annoyed and a small proportion choosing ‘extremely’ annoyed.

0 20 40 60 80 100

Not at all

Slightly

Moderately

Very much

Extremely


Sta

ff p

erc

ep

tio

n o

f n

ois

e a

nn

oy

an

ce

D8 (n=21)

N3 (n=10)

M4 (n=10)

Figure 9.33 Staff perception of noise in terms of annoyance



rated a noise event with a 2, 3 or 4, and so could be said to be more than a little annoyed by the

event.

It can be seen that the four events rated by a high percentage of staff in Ward M4 were the doorbell

(80%), internal telephone (70%), medical equipment alarms (60%), and the nurse call (60%). Staff in

wards N3 and D8 also rated these events, but the percentage of those annoyed by the internal

telephone, nurse call and medical equipment alarms was 10 - 20% lower. The doorbell was not a

major source of annoyance on wards N3 and D8.


___________________________________________________________________________________________________________________

190

Other events cited by 30% or more staff on the wards were people talking, and staff talking on the

telephone. Visiting time; the talking on and ringing of mobile phones; and TV / radio use were all rated

more highly in wards D8 and N3 than M4. This maybe an indication of a more lenient approach by

ward staff.

Some anomalies can be seen in Figure 9.34. Trolleys, footsteps, rubbish bins and external noise were

all cited as annoying by 40% of respondents in N3, but much less so (or not at all) in the other wards.

The timber floor construction of N3 is thought to increase the noise of trolleys and footsteps in this

ward, as discussed in Section 9.5.1. External noise annoyance may have been exacerbated as the

study was carried out during warmer weather in this ward and so more windows may have been open

at the time of the survey.

0 10 20 30 40 50 60 70 80 90 100

External noise

Doors banging

Internal telephone


Nurse call

Doorbell

Footsteps

Medical Equipment

People talking

Cleaning

Rubbish bins

Trolleys

Meal times

TV / radio



Visiting time


D8 (n=21)

N3 (n=10)

M4 (n=10)

Figure 9.34 The percentage of staff rating an annoyance noise event with a 2, 3 or 4

9.9.3. Interference with work

Respondents were asked to what extent noise interfered with their ability to work effectively. As can

be seen in Figure 9.35, opinion of the respondents in all the wards was very split, with staff in ward D8

seemingly slightly more adversely affected by noise than in the other wards, with 33% choosing

‘moderately’.


___________________________________________________________________________________________________________________

191

0 20 40 60 80 100

Not at all

Slightly

Moderately

Very much

Extremely


Sta

ff p

erc

ep

tio

n o

f n

ois

e i

nte

rfe

ren

ce

D8 (n=21)

N3 (n=10)

M4 (n=10)

Figure 9.35 Staff perception of the extent to which noise interferes with work


job effectively (again the rating scale of 0 to 4 was used). Figure 9.36 shows the percentages of staff

who rated a noise event with a 2, 3 or 4, and so it could be said that this noise event interfered to

some extent with their ability to carry out their job effectively.

0 10 20 30 40 50 60 70 80 90 100

External noise

Doors banging

Internal telephone


Nurse call

Doorbell

Footsteps

Medical Equipment

People talking

Cleaning

Rubbish bins

Trolleys

Meal times

TV / radio



Visiting time


D8 (n=21)

N3 (n=10)

M4 (n=10)

Figure 9.36 The percentages of staff rating an interference noise event with a 2, 3 or 4


___________________________________________________________________________________________________________________

192

It can be seen that the numbers of staff rating events as interfering with their work are generally fewer

than for annoyance. However, the internal telephone is still consistently rated by 50% or more staff,

with visiting time and the nurse call both still rated by 30% or more respondents in each ward. Medical

equipment, which was rated as annoying by 50% or more, is rated less severely in the case of

interference, presumably as staff feel that they need to hear these alarms to make necessary

decisions.

There are several anomalies worth noting. TV / radio usage, trolleys, rubbish bins, footsteps, doors

banging and external noise are all rated by more staff in Ward N3. As mentioned in relation to

annoyance, some of these events may be exacerbated by the construction of the timber floor.

Banging doors has also shown to be a problem specifically in the area surrounding the nurse station

in this ward (see Section 9.6.1).





Figure 9.37 shows the mean ratings for each noise event. It can be seen that ‘patients calling out’

were considered by staff in all wards to be the most important noise event. However, the average

ratings were consistently high in all cases suggesting that all of these events are important for staff.

0

1

2

3

4

Nurse call Conversations

with colleagues

Conversations

with patients

Medical

equipment

alarms

Patients calling

out

Patient activity

D8 (n=20)

N3 (n=11)

M4 (n=10)



___________________________________________________________________________________________________________________

193

9.10. Results of the patient questionnaires

With the help of the ward clerks, questionnaires were distributed to those patients who had been on

the ward for over 24 hours and were judged to be physically and mentally fit enough to complete the

survey. In total 74 patients completed the questionnaire: 47 in Ward D8; 13 in Ward N3; and 14 in

Ward M4.

The following sections discuss results from the patient questionnaires and examine the differences

between perceptions on the three wards.

9.10.1. Patient profiles

As with the staff questionnaire, the first section aimed to establish certain attributes about the

patients, beginning with the question of gender. As discussed previously, wards D8 and N3 are split

male / female wards and ward M4 is predominantly male. This is shown clearly in Figure 9.38 below:

0 20 40 60 80 100

Male

Female

Percentage (%)

D8 (n=47)

N3 (n=13)

M4 (n=14)

Figure 9.38 Gender split by ward type

Respondents were asked for their age range, and as shown in Figure 9.39, a high percentage of

patients were older, with 60% in the respiratory ward (N3), and 50% in wards D8 and M4 aged 60

years or above.

0 10 20 30 40 50 60 70

< 20

20-30

31-40

41-50

51-60

60+

Percentage (%)

Ag

e r

an

ge

D8 (n=47)

N3 (n=13)

M4 (n=14)

Figure 9.39 Patients age by band


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194

Respondents were asked how long they had been on the ward, and it can be seen in Figure 9.40 that

the majority had been on the ward for less than one week. Ward D8 shows the longest stay patients,

which is unsurprising due to the variety of conditions treated on this ward, with some patients

admitted for elective surgery and others on the ward as a result of a serious accident, where recovery

may be substantially longer. Length of stay in Ward N3 is more likely to be more variable, with some

patients suffering from very serious respiratory conditions remaining on the ward for several weeks.

Ward M4 is a surgical ward where the procedures utilised are of a more standard nature. As such

patients on this ward tend to be discharged more quickly.

0 20 40 60 80 100

< 1 week

1- 2 weeks

2 - 3 weeks

3+ weeks

Percentage (%)

Le

ng

th o

f st

ay

D8 (n=47)

N3 (n=13)

M4 (n=14)

Figure 9.40 Length of patient stay when completing the questionnaire

The presence of a hearing impairment was also explored, with 39% of respondents on Ward D8, 31%

on N3 and 14% on Ward M4 indicating that they did suffer to some degree. The high incidence of

hearing impairment on wards D8 and N3 probably reflects the age profile on these wards. However it

is not clear why the incidence is lower on ward M4 which has a similar age distribution; it may be due

to the fact that the majority of patients on this ward are male and may be more reluctant to admit to a

hearing problem.

The bed number of the respondent was noted on the front of the questionnaire by the ward clerk. This

number provided useful location information which is considered when investigating relationships

between bed positioning and patient accommodation type and noise annoyance and disturbance,

which are explored in Chapter 11. In terms of the single room / multi bed bay split, 99% of

respondents in Ward D8 were staying in multi-bed bays, with 85% in each of the wards N3 and M4.

9.10.2. Noise annoyance and disturbance

The questionnaire sought to identify the sources of noise that may annoy or disturb patients.

Respondents were given two lists of noises and were asked to rate the day time annoyance and night

time disturbance on a scale of 0 to 4 (where 0 indicated no annoyance / disturbance and 4 indicated a


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195

great deal). Several lines were left blank at the bottom of the lists for patients to add and rate

additional noise sources.

Patients were first asked how they perceived the day time noise environment on the ward. Figure 9.41

details the responses, which shows over 60% of patients in Ward D8 found the ward ‘a little noisy’,

with similar percentages finding Wards N3 and M4 to be ‘quiet’. Interestingly, when asked whether

they were annoyed by noise, a relatively low percentage (26%) of patients in Ward D8 felt annoyed,

with even lower percentages of 15% and 21% of patients in Wards N3 and M4 respectively.

0 20 40 60 80

Very quiet

Quiet

A little noisy

Very noisy

Extremely noisy

Percentage (%)

Pa

tie

nt

pe

rce

pti

on

of

the

da

yti

me

wa

rd

en

vir

on

me

nt

D8 (n=47)

N3 (n=13)

M4 (n=14)

Figure 9.41 Patient perception of the day time ward noise environment



and 4 indicating ‘a great deal’. With relatively small patient samples in wards N3 and M4, the number

of people annoyed by day time noise was too low for any meaningful analysis (n=2 and n=3

respectively). However in ward D8, which had a larger sample, 12 patients rated day time noise as

annoying, and consequently their ratings are worth examining further. Figure 9.42 shows the

percentage of patients within this sample who rated a noise event with a 2, 3 or 4, and as such could

be said to be more than a little annoyed by the event.


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196

0 10 20 30 40 50 60 70 80 90 100

External noise

Doors banging

Internal telephone


Nurse call

Footsteps

Medical Equipment

People talking

Cleaning

Rubbish bins

Trolleys

Visiting time

Meal times

TV / radio



Patients crying out

% of patients who rated each event 2 or above in terms of day time noise annoyance

D8 day time annoyance (n=12)

Figure 9.42 The percentages of patients on Ward D8 rating an annoyance noise event

with a 2, 3 or 4

It can be seen that patients crying out and the internal telephone are the most highly rated noise

events, with nearly 60% of patients in the sample annoyed by each source. Ward D8 has a female

only elderly trauma unit of 13 beds, with any elderly male patients admitted on the ward sharing the

same bay accommodation as the other male patients. Many of the elderly patients suffer from a

degree of confusion or dementia and are likely to cry out, but of course patients who are in a great

deal of discomfort will also vocalise their pain.

There are four internal telephones at the main nurse station in Ward D8, and in some of the other

patient bays there are staff desks with a telephone. If these phones are left unanswered, or take some

time to divert, this could explain this level of annoyance. Visiting time, medical equipment alarms and

people talking are also cited as annoying by over 30% of patients in this ward.

Two patients in Ward D8 added an additional noise event that they themselves found to be annoying

during the day. The events were:

� Staff in a ‘performing mood’

� External building work

Patients were asked how they perceived the night time noise environment on the ward. Figure 9.43

details the responses, which can be seen to be a little more split than for daytime noise annoyance,

with several patients having more extreme perceptions of night time noise.


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197

When asked whether they were disturbed by noise at night, 51% of patients in Ward D8; 33% of

patients in Ward N3; and 57% of patients in Ward M4 felt they were. Thus overall approximately 50%

of patients were disturbed by noise at night; this figure is similar to that in Bedford Hospital.

0 10 20 30 40 50

Very quiet

Quiet

A little noisy

Very noisy

Extremely noisy

Percentage (%)

Pa

tie

nt

pe

rce

pti

on

of

the

nig

ht

tim

e w

ard

en

vir

on

me

nt

D8 (n=47)

N3 (n=13)

M4 (n=14)

Figure 9.43 Patient perception of the night time ward noise environment



indicating ‘a great deal’. Sample sets were higher than for the day time annoyance with n=23 for Ward

D8, but were small for wards N3 and M4 (n=5 and n=7 respectively). Again it is possible that in these

cases, only those patients who had felt they had something specific to say about noise may have

chosen to take part in the survey, therefore skewing the results to a degree.

Figure 9.44 shows the percentages of patients within these samples who rated a noise event with a 2,

3 or 4, and so could be said to be more than a little disturbed by the event.

It can be seen that of those patients who were disturbed by night time noise in Ward D8, around 40%

of respondents found that patients crying out, people talking, medical equipment alarms and the

internal telephone were disturbing. This was a very different split to the other wards. In Ward M4 it

was the internal telephone that was rated as disturbing by the most respondents – over 70%. This far

exceeded the ratings for any other sources of disturbance on Ward M4, with doors banging, staff

talking on the telephone and patients crying out, rated by around 30%. Ward N3 again showed

differences, with the nurse call system cited as disturbing by the highest percentage of patients

(60%), and trolleys, people talking, medical equipment and doors banging cited by 40% of

respondents.


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0 10 20 30 40 50 60 70 80 90 100

External noise

Doors banging

Internal telephone


Nurse call

Footsteps

Medical Equipment

People talking

Rubbish bins

Trolleys

TV / radio



Patients crying out

% of patients rating night time disturbance event of 2 or above

D8 night time annoyance (n=23)

N3 night time annoyance (n=5)

M4 night time annoyance (n=7)

Figure 9.44 The percentages of patients rating a disturbance noise event with a 2, 3 or 4

It can be seen that ‘mobile phones ringing’, ‘talking on mobile phones’ and ‘rubbish bin’ noise are

cited as a disturbance only on Ward D8. It is possible that, with regards to the use of mobile phones

on this ward, the policy may be more lenient than on wards N3 and M4. Also, the rubbish bins in this

ward are possibly older metal bins, rather than bins of a newer, quieter design installed in some of the

more recently built wards.

Four patients added an additional noise event that they themselves found to be disturbing at night.

The events were:

� Snoring (D8)

� Generally noisy bed neighbours (D8)

� Vibration of the floor (N3)

� Nurses talking (N3)

Interestingly, the timber floor construction in Ward N3 does appear to add to the disturbance in some

cases, with a patient specifically citing vibration of the floor, and higher numbers of patients on this

ward disturbed by trolleys (40%) and footsteps (20%) than on Wards D8 and M4.


Looking at sound in a positive rather than in a negative light, patients were asked if there were any

sounds that they actually found comforting. Most patients left the answer blank (70% in ward D8; 77%

in ward N3; and 86% in M4), however, there were nineteen completed responses which were similar


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199

in content to those from Bedford Hospital. Responses included listening to music on the radio,

knowing that the nursing staff were nearby to provide care, the tea trolley, droning sounds (such as

the hoover and floor cleaner), and maintaining some connection with the outside world. The full

responses can be seen in Appendix B.

Respondents were also asked if they felt that there was ever too little sound in a room. Only three

patients in total said that they did. Unfortunately, two of these patients did not complete the details

regarding their accommodation, but the other respondent was in a single room.

9.10.4. Ease of hearing and privacy

Patients were asked whether high levels of background noise may at times make it difficult to hear

doctors and nurses who talk to them. 42% of respondents on Ward D8 felt that this was the case, with

this percentage made up of 12 hearing impaired patients and six patients who did not indicate any

hearing problem. On Wards N3 and M4 however, only one respondent from each felt that high levels

of background noise made it difficult to hear, and both these patients were hearing impaired.

Conversational privacy was investigated by asking whether the patient felt that they could have a

private conversation at their bedside. The lowest percentage of patients who felt they could speak

privately was in Ward D8 (59%), which is unsurprising given the bay sizes and bed spacing in this

ward. Out of those who felt they could speak privately, 56% of patients on this ward felt that they

would need to lower their voice. On wards N3 and M4, 69% and 79% of patients respectively felt that

they could speak privately at their bedside. Out of those who felt they could speak privately, 71% on

Ward N3 and 73% on Ward M4 felt that they would have to lower their voice. All respondents in single

patient rooms on these wards (n=4) were happy with conversation privacy.

9.11. Questionnaire comments

Staff and patients were invited to make additional comments at the end of the questionnaire if they

wished. Very few staff made comments, but many patients did leave some feedback which was very

varied. Several patients cited noise from the wearing of high heeled shoes; crying out and shouting of

other patients was disturbing or distressing; and noise attributable to visiting times and the lack of

enforcement of visiting hours by staff was mentioned by several patients; A detailed list of these

comments is shown in Appendix B.

9.12. Summary

This section summarises the main findings from the study of the three wards at Addenbrooke’s

Hospital:

� The nurse station in Ward D8, had the highest average noise levels of all the nurse stations

measured in the three study wards, with day time levels of around 58 dB LAeq and night time

levels of around 53 dB LAeq. Typical sources of noise here included high levels of conversation,


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200

administrative tasks, furniture scraping on the floor and the closing of desk drawers. The nurse

station in ward N3 had the lowest measured levels, with day time levels of around 53 dB LAeq and

night time levels of around 47 dB LAeq. 48% of high level noise events captured here were due to

the banging of the clean and dirty utility room doors, and so levels could be lowered still further,

with different opening mechanisms installed on these doors. The smaller nurse station in Ward

M4, also suffered from noise due to the banging of the dirty utility room door. Other sources of

high level noise captured at the nurse stations in this ward were primarily due to high levels of

conversation, and corridor traffic.

� Noise level measurements made in the multi-bed bays in Ward D8 were consistently higher both

during the day and night than on the other wards. This ward provided a mixture of patient

accommodation with 3-bed, 4-bed, 7-bed and 12-bed bays. Noise levels were very consistent

throughout , and did not appear to be affected by the number of patients occupying the bays,

with some of the highest levels measured in a 3-bed bay for elderly patients. Many of the high

level noise events identified were related to activity at the nurse’s desk in the 12-bed bay, and

confused elderly patients crying out in the bays in the elderly trauma unit.

� Noise levels measured in the multi-bed bays in Wards N3 and M4 were similar, with day time

levels of around 53 dB LAeq and night time levels of around 44 dB LAeq, with little variation

between the bays. However, subsequent investigation of the numbers of high level noise events

recorded in each bay indicated differences in the noise climate.

� Single rooms were found to have less consistent patterns of noise levels which in some cases

were found to be higher than those measured in multi-bed bays. Staff activity, and patient and

visitor behaviour was shown to be the main reason for this.

� All measured levels in the patient accommodation were above those suggested by the WHO

guidelines and the day / night division specified by the WHO did not appear to be realistic.

� Over 50% of staff in all three wards rated medical equipment alarms and the internal telephone

as annoying noise events, with people talking and staff talking on the telephone rated by 30% of

respondents in each ward. However, opinion on the annoyance of other noise sources was more

split. High percentages of staff on Ward M4 rated both the nurse call and ward doorbell as

annoying; whereas more staff in wards D8 and N3 rated visiting time, the use of mobile phones

and of TV / radio. In the modular ward, Ward N3, higher percentages of respondents rated the

noise from trolleys, footsteps and external noise as annoying than on the other two wards. Noise

of footsteps and trolleys may be magnified on this ward by the construction of the timber floor.

� 62% of patients in Ward D8 found the ward to be ‘a little noisy’ during the day, with patients

crying out, the internal telephone ringing and visiting time cited as the most annoying events,

whereas on wards N3 and M4, over 60% of patients found the wards ‘quiet’ or ‘very quiet’ during

the day.


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201

� Of those questioned, 51% of patients in Ward D8; 33% of patients in Ward N3; and 57% of

patients in Ward M4 felt that they were disturbed by noise at night. Opinion was split with patients

crying out, people talking, medical equipment alarms and the internal telephone disturbing

patients in Ward D8; the internal telephone far outranking any other source of noise disturbance

in Ward M4; and the nurse call system cited as disturbing by the highest percentage of patients

in Ward N3, followed by medical equipment alarms, people talking and doors banging.

9.13. Conclusions

As in Bedford Hospital, noise level measurements and questionnaire surveys have confirmed that

noise is a problem in both medical and surgical wards. Staff responses indicate that they are annoyed

by noise, and a significant number of patients questioned felt that they were disturbed by noise during

the night, a time when they should be able to rest and recuperate.

Noise levels did not appear to be related to occupancy levels, with similar levels measured in both

four and six bed bays, and higher levels measured in single patient rooms than in the multi-bed bays

on occasions.

Much of the high level noise identified could be reduced with changes to behaviour, correct

enforcement of hospital policies, simple improvements to design and maintenance of equipment. This

is discussed further in Chapter 12.

The following chapter investigates the use of the Maximum Likelihood Estimation method to estimate

reverberation times in occupied wards using the data captured during the study.

Acoustic Design for Inpatient Facilities in Hospitals Blind estimation of reverberation time

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202

10. Blind estimation of reverberation time

10.1. Introduction


important measurement in the field of room acoustics. There are several standard methods used to

calculate the RT of a room, however these rely on generating high level noise, which would be

unacceptable in an occupied hospital ward. All of the wards taking part in the main study were at

capacity at all times and therefore it was not possible to make physical RT measurements in these

wards.

An alternative estimation technique was identified that could possibly be used with some of the noise

measurement data collected in the study wards. The method was developed at Salford University

(Kendrick, Cox and Li, 2007; Kendrick et al, 2011) and is known as the Maximum Likelihood

Estimation (MLE) method. The technique had been successfully used to estimate a number of

acoustic parameters ‘blind’ (including RT), by using sounds already present in a room such as speech

or music.

As discussed in previous chapters, the noise measurement data collected from the wards contained

numerous discrete sound files or ‘trigger files’, created when LAmax exceeded 70 dB. These files were

between six and ten seconds in length and contained sounds such as speech; impulsive noises, for

example, rubbish bins, doors banging and dropped objects; bed rails; and other sounds associated

with general movement in a space. It was thought that these trigger files may be suitable for use with

the MLE algorithms, and therefore could potentially be of use in estimating the RT20 (MLE-RT20) of the

occupied wards. However, extensive validation would be required to prove that accurate estimates

could be obtained.

This chapter begins by describing the validation of the MLE-RT20 method using measurement data

from the surveys of Bedford and Addenbrooke’s Hospital and from a simulated hospital environment.

Following the discussion of the validation, the maximum likelihood method is used to estimate

reverberation times for a number of occupied study wards.

10.2. Initial validation

The MLE-RT method works by identifying short periods of reverberant decay within a noise dataset

where the dynamic range is greater than 25 dB. Data selection techniques are used to ensure correct

recognition of suitable decay phases, and the mean RT is estimated from multiple values. To ensure

estimates are accurate, the method relies on a large amount of suitable data. More details of the

method are provided by Kendrick (2009; 2011).


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203

As the MLE-RT method was initially developed for use with speech or music, it was unknown whether

it would work with the trigger files collected. It was thought that if the files were of a reasonable sound

quality, and enough suitable decays could be identified, then the discrete nature of the files would not

necessarily prevent the method from working. Consequently, trigger files collected during noise

measurements in a 4-bed bay during the pilot study were sent for initial processing.

The sound level meter (SLM) had a number of settings which could be adjusted to change the format

and quality of the audio file recordings. These settings included three different word lengths of 8, 16

and 24-bit; two sampling frequencies at 12 kHz and 48 kHz; and the recording gain. The word length

and sampling frequencies affect the size of the file, and so with limited storage available on the meter,

these had been initially set to minimum values for the pilot study. The gain setting increases the

loudness of the recorded sound file, and had been set fairly high, to ensure playback on a laptop

would be easily audible during analysis.

Following the initial processing of the trigger files, a number of issues with the data were found. The

low quality of the audio recording caused a number of dropouts, and the high gain setting caused a

certain amount of clipping. Both these issues needed to be resolved before the data would work with

the MLE algorithms. It was felt however, that the type of sounds recorded would be suitable, and if the

audio issues were resolved, the data would probably be capable of yielding some reasonable results.

The audio quality settings were subsequently changed to 24-bit sampling at a frequency of 12 kHz

with a gain of 24 dB. These were considered to be the optimal settings in terms of both audio quality

and file size, and would allow estimations up to 4 kHz to be computed. With confidence in the discrete

data files established, the next step was to perform a simulation experiment to compare the accuracy

of estimated MLE-RT values with RTs measured in a laboratory space. This is discussed in the next

section.

10.3. Validation using real and simulated measurements

To test the accuracy of the estimated RT values against those measured, a scenario was developed

that would allow both real time RT measurements to be made along with the recording of noise data

consisting of the type of sounds that would be found in an occupied hospital ward.

A new building had recently opened at London South Bank University, which was used in part for

nurse training. Several clinical skills laboratories were laid out as hospital wards to provide students

with clinical practice space. Each laboratory was equipped with standard hospital furniture including

beds with rails, bed tables, dustbins, sinks, privacy curtains and wheeled equipment. It was thought

that within this environment it would be easy to create a noise climate similar to that of an occupied

ward. This would allow enough trigger files to be captured to provide data for the MLE-RT method.

Real time RT measurements could also be made using an impulsive noise source and the results


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compared to the estimates generated. Two validation experiments were carried out and are discussed

in the following sections.

10.3.1. Validation 1

The clinical skills laboratory used for the first validation, shown in Figure 10.1, had a volume of 171

m3. The ceiling was exposed concrete soffit; the floor was concrete with a heavy duty vinyl covering;

and the walls were plasterboard. As can be seen from Figure 10.1, the room was fully furnished, and

included dummy patients in the beds.

Figure 10.1 Clinical skills laboratory used for validation 1

RT measurements were made using thick latex balloons as an impulsive noise source. Six

measurements were made; with three source and two receiver positions. Figure 10.2 shows the

spatially averaged RT20 values over third octave bands from 250 Hz to 4 kHz as stipulated in BS EN

ISO 3382-2 (2008). At 500 Hz and above the 95% confidence limits for each RT20 value are within

±0.1 s, suggesting good accuracy at these frequencies. However, accuracy at 250 to 400 Hz is lower,

with slightly more measurement variation at these frequencies.

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

250 315 400 500 630 800 1 k 1.25 k 1.6 k 2 k 2.5 k 3.15 k 4 k

RT

20 (

s)

Frequency (Hz)

Figure 10.2 Average RT20 measurements with 95% confidence limits (Impulse Response Method)


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A 60 minute noise measurement was made within the room during which noise was created that

would be comparable to that found in an occupied hospital ward. Noise included conversation; moving

of furniture and bed rails; use of rubbish bins and sinks; dropping objects; and opening and closing of

doors. During this measurement period 149 trigger files (sound files where LAfmax exceeded 70 dB)

were created, totalling approximately 20 minutes in length. This data was sent to the University of

Salford for processing.

Table 10.1 shows both the measured and estimated RT values and the difference between them. Due

to the processor intensive nature of the algorithm used in the MLE-RT method, only octave band RT

values are estimated.

Table 10.1 Comparisons between measured and MLE-RT20 values

Frequency

(Hz)

Measured

T20 (s) MLE-RT20 (s)

Difference

(s)

250 0.712 0.710 -0.002

500 0.712 0.828 0.116

1000 0.706 0.771 0.065

2000 0.722 0.702 -0.020

4000 0.707 0.709 0.002

It can be seen that the results show reasonable accuracy with less than 0.1 s difference in the

majority of cases (differences greater than 0.1 s are highlighted in green). The value 0.1 s is of

particular significance when estimating RT values because of the subjective difference limens.

Kendrick (2009; 2011) discusses that in order to judge the performance of a measurement method it

must be compared against the ability of the human ear to detect subtle changes in acoustic

conditions. Subjective difference limens are the smallest change in a parameter value that can be

detected and are determined using ‘just noticeable differences’. Bork (2000) shows that in a room with

an RT value of 2 s or less, the subjective difference limen is 0.1 s, and hence any change in the RT

that is less than 0.1 s would be inaudible to the listener.

10.3.2. Validation 2

Following the positive results obtained during the first validation, it was felt that further simulations in

different acoustic conditions would be required to reinforce the initial outcome. Another clinical

laboratory of different dimensions (153 m3) was available for use and it was decided to perform

several sets of tests within this room. Apart from the room volume, the layout and finishes were

identical to those of the first room used.

To ensure as much data as possible was collected, the acoustic room conditions were varied. This

was achieved by fully drawing the privacy curtains around the beds during one test scenario and then

opening all the curtains for a second scenario. Two identical Norsonic 140 sound level meters (SLM1


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206

and SLM2) were used to make noise level measurements of the simulated hospital sounds. The

meters were situated on different sides of the room and hence captured slightly different levels, thus

providing further data for validation purposes.

Two sets of real time RT measurements were made using the same impulse response method as in

the previous validation; one set with the privacy curtains open; the other with the curtains drawn. As

before, six measurements were made in each case; with three source and two receiver positions. The

measured results were found to be consistent above 500 Hz, with 95% confidence limits for each

mean RT20 value within ± 0.1 s, but with some inconsistencies found at 500 Hz and below, as shown

by Figure 10.3. It can be seen that as a result of drawing the curtains, RT20 values were reduced by

between 0.1 s and 0.3 s.

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

250 315 400 500 630 800 1 k 1.25 k 1.6 k 2 k 2.5 k 3.15 k 4 k

RT2

0 (

s)

Frequency (Hz)

Curtians drawn

Curtains open

Figure 10.3 Average RT20 measurements with 95% confidence limits (Impulse Response Method)

Two 60 minute noise measurements were made within the room on each SLM, with curtains open

and curtains drawn. Again noise was created that would be comparable to that found in an occupied

hospital ward. Table 10.2 shows the number of trigger files recorded during each scenario by each

SLM.

Table 10.2 Numbers of triggers recorded during the simulations

Number of trigger files recorded

Curtains open

Curtains drawn

SLM 1 188 164

SLM 2 233 196

The trigger files recorded were used to provide MLE-RT20 estimates for the four scenarios. The

estimates were compared with the actual measured values and the results can be seen in Tables

10.3 to 10.6. Differences greater than 0.1 s are highlighted in green.


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207

Table 10.3 SLM 1 with curtains open Table 10.4 SLM 1 with curtains drawn

Frequency (Hz) Measured RT20 (s) Estimated RT20 (s) Difference (s) Frequency (Hz) Measured RT20 (s) Estimated RT20 (s) Difference (s)

250 0.775 0.752 -0.023 250 0.684 0.660 -0.024

500 0.812 0.949 0.137 500 0.704 0.628 -0.076

1000 0.861 1.004 0.143 1000 0.645 0.640 -0.005

2000 0.910 0.904 -0.006 2000 0.646 0.734 0.088

4000 0.921 0.963 0.042 4000 0.659 0.619 -0.040

SLM 1 - Curtains Open SLM 1 - Curtains Drawn

Table 10.5 SLM 2 with curtains open Table 10.6 SLM 2 with curtains drawn

Frequency (Hz) Measured RT20 (s) Estimated RT20 (s) Difference (s) Frequency (Hz) Measured RT20 (s) Estimated RT20 (s) Difference (s)

250 0.775 0.794 0.019 250 0.684 0.652 -0.032

500 0.812 0.928 0.116 500 0.704 0.778 0.074

1000 0.861 0.940 0.079 1000 0.645 0.672 0.027

2000 0.910 1.067 0.156 2000 0.646 0.666 0.020

4000 0.921 1.014 0.093 4000 0.659 0.692 0.033

SLM 2 - Curtains Open SLM 2 - Curtains Drawn

The results show good accuracy with the curtains drawn, but slightly less so with the curtains open,

with two octave frequency bands showing a difference slightly above 0.1 s in each case, which is just

outside the difference limen for RT. It is thought that this is primarily due to the number of suitable

decay phases with a sufficient signal to noise ratio available for analysis at these frequencies.

Figure 10.4 further illustrates the accuracy of the MLE-RT20 estimates, by plotting the estimated

values against the measured values. The 0.1 s difference limens are represented by dashed lines.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4

MLE

-RT

20

(s)

Measured T20 (s)

SLM1 - Curtains open SLM1 - Curtains closed SLM 2 - Curtains open SLM2 - Curtains closed

Figure 10.4 Accuracy of RT20 estimations in relation to actual measured values


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208

10.3.3. Validation study conclusions

The validation study demonstrated that with the change of audio settings, the trigger file data could be

successfully analysed using the MLE-RT20 method. The accuracy of the estimates was reasonable

overall, but some small inconsistencies were found for the different room conditions. This was

primarily due to insufficient data with suitable regions of decay. Given that the data captured in the

simulation was captured for a relatively short time period (60 minutes) and that measurements made

during the main study were over a seven day period, it was considered likely that sufficient data would

be available to provide reliable estimates of reverberation times in occupied hospital wards.

10.4. Estimation of RT in occupied hospital wards

The validation study described in the previous section yielded on average 1.4 samples of data with

suitable free reverberant decay per minute. Examination of the trigger files from the occupied wards

showed the density of suitable data was approximately eight times less than in the validation study.

Previous testing of the MLE-RT20 method had established a minimum amount of suitable data needed

to produce accurate estimates, and when this was applied to the hospital data it was calculated that at

least forty hours of measurement data would be required to provide enough suitable decays. As

discussed previously, the measurement data collected from the occupied hospital wards was over a

period of approximately seven days, and as such should provide ample data to produce an accurate

estimate of RT. Table 10.7 shows the data available for use with the MLE-RT20 method, which

consisted of data from 17 different spaces. Data was not available from all wards due to poor quality

audio files.

Table 10.7 Locations with data available for MLE-RT20 estimation

Hospital Ward Areas for which MLE-RT data is

available

Addenbrookes D8 2 x 3-bed bays, 1 x 4-bed bay, 1 x 7-bed bay,

1 x 12-bed bay

Addenbrookes N3 3 x 4-bed bays, 2 x single rooms

Bedford Surgical 2 x 4-bed bays, 1 x 6-bed bay, 2 x single rooms, nurse station

Bedford Medical Pre and post ceiling tile change in 4-bed bay

10.4.1. Methodology

For each room, the trigger files captured over the entire measurement period (generally seven days),

were segmented into two groups: from 06.00 to 18.00 (day); and from 18.00 to 06.00 (night). The day

and night split chosen was not the same as was used in rest of the study, as too little data would exist

for the period 23.00 to 07.00 for estimation purposes. Data was grouped in this way for two reasons:

(i) to reduce the possibility of compromising day time estimates with potentially less accurate night


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209

time estimates (due to the lower amount of suitable data available at night); (ii) to allow comparisons

to be made between day and night time estimates (given that night time data was found to be

sufficiently accurate). This comparison could yield interesting information regarding the effects of ward

conditions on the MLE-RT20 estimates, mostly in relation to occupancy levels (no visitors and less

clinical and domestic activity at night and hence less acoustic absorbency).

Estimates were computed for octave frequency bands 250 to 4000 Hz, for the two groups of data.

Lower frequencies were discarded, as previous experience of this method with other data sets

showed inaccuracies at frequencies less than 250 Hz.

For each data group, initial estimates were calculated from suitable decays captured during four hour

windows of data. An example of this can be seen in Table 10.8 for the day time data. The final MLE-

RT20 estimate for each day and night group was computed by calculating the mean of all the

estimates over the measurement interval.

Table 10.8 Day time data shown in 4 hour windows; overall mean estimate

with 95% confidence intervals

Mean RT 06.00 - 10.00 10.00 - 14.00 14.00 - 18.00 06.00 - 10.00 10.00 - 14.00 14.00 - 18.00 06.00 - 10.00 10.00 - 14.00 14.00 - 18.00

250 0.500 0.520 0.637 0.332 0.365 0.483 0.445 0.591 0.585 0.539 0.057

500 0.514 0.720 0.500 0.483 0.526 0.461 0.406 0.509 0.568 0.559 0.047

1000 0.541 0.604 0.611 0.494 0.512 0.596 0.455 0.663 0.614 0.579 0.034

2000 0.434 0.693 0.486 0.571 0.652 0.621 0.590 0.649 0.697 0.632 0.041

4000 0.436 0.530 0.416 0.605 0.451 0.510 0.586 0.573 0.621 0.554 0.037

95% CL

(7 days)

Frequency

(Hz)

Day 1 06.00 - 18.00 Day 2 06.00 - 18.00 Day 3 06.00 - 18.00

It has been shown (Kendrick 2009), that by calculating the standard error of these estimates, and by

only accepting measurements where the 95% confidence limits are within ±0.1 s, very good accuracy

is obtained.

10.4.2. MLE-RT20 estimates from day time data

This section graphically presents MLE-RT20 estimates from three different study wards; examines the

accuracy of the estimates; and discusses the effects of the different levels of acoustic absorbency on

the wards.

Figure 10.5 shows the MLE-RT20 day time estimates for five multi-bed bays on Ward D8 at

Addenbrooke’s Hospital. It can be seen that the estimates are between 0.4 s and 0.57 s at 1 kHz. The

majority of estimates have low 95% confidence intervals of around ±0.05s, suggesting that the

estimated RTs are accurate. All 95% confidence intervals calculated for the estimates are within the

±0.1 s difference limen.

This particular ward has little in the way of acoustic absorbency at ceiling level. As explained in

Chapter 9, most ceilings in this ward consist of metal pan tiles which work in conjunction with the

heating system, by radiating heat from the hot water pipes running above them. These tiles are

perforated, and have a layer of insulation covering the water pipes which may provide a level of

acoustic absorbency at some frequencies. The 4-bed bay which is situated behind the nurse station


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210

has a suspended ceiling grid with solid plaster tiles. It can be seen that it is the larger volume multi-

bed bays with more occupants and hence more absorption, which have the lowest MLE-RT20

estimates, as would be expected.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Est

ima

ted

MLE

-RT

20

(s)

Octave band (Hz)

3-Bed Bay A

3-Bed Bay B

4-Bed Bay

7-Bed Bay

12-Bed Bay

250 500 1000 2000 4000

Figure 10.5 MLE-RT20 estimates for five multi-bed bays in Ward D8, Addenbrooke’s Hospital

(day time data) with 95% confidence limits

Figure 10.6 shows MLE-RT20 estimates for six locations in Ward N3 at Addenbrooke’s Hospital. It can

be clearly seen, that the estimates for 4-bed bay B and single room J are higher than for the other

locations and also have larger confidence intervals, particularly at 250 Hz, where they are greater

than ±0.1 s. As this data falls outside the stipulated ±0.1 s confidence limits, it must be assumed to

be inaccurate and therefore should be ignored. However, the majority of estimates have low 95%

confidence intervals with a mean of ±0.04s, which suggests that the estimated values are accurate.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Est

ima

ted

MLE

-RT

20

(s)

Octave band (Hz)

4-Bed Bay A

4-Bed Bay B

4-Bed Bay C

Single Room J

Single Room K

250 500 1000 2000 4000

Figure 10.6 MLE-RT20 estimates for six locations in Ward N3, Addenbrookes Hospital (day time

data) with 95% confidence limits


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211

The MLE-RT20 estimates at 1 kHz show much lower RTs than in Ward D8, with all estimated values of

around 0.25 to 0.3 s. All these areas have suspended ceilings with good quality acoustic ceiling tiles.

Figure 10.7 shows MLE-RT20 estimates for seven locations in the surgical ward at Bedford Hospital.

The estimate for 4-bed bay 1 shows confidence intervals which are greater than ±0.1 s at 250 Hz and

therefore this data should be ignored. However, this is the only estimate for the ward where the ±0.1 s

confidence limits were exceeded, with most confidence limits generally low, with values less than

±0.04 s.

The MLE-RT20 estimates at 1 kHz for the nurse station and 4-bed bay 1 show the lowest estimated

values of around 0.25 to 0.3 s. These areas both have a suspended ceiling with acoustic ceiling tiles

and it can be seen that the values are similar to those in Ward N3 at Addenbrooke’s Hospital (see

Figure 10.6), which also had acoustic ceiling tiles. The single rooms and 6-bed bay 3 are similar with

a low value of around 0.35 s. These rooms have either solid plaster ceilings (6-bed bay 3 and single

room 1) or a non acoustic suspended ceiling (single room 3). 4-bed bay 4 has noticeably higher

estimates at all frequencies, with an MLE-RT20 estimate of 0.55 s at 1 kHz. This bay has been

refurbished more recently and has reflective, plaster ceiling tiles throughout.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Est

ima

ted

MLE

-RT

20

(s)

Octave band (Hz)

4-Bed Bay 1

4-Bed Bay 4

6-Bed Bay 3

Single Room 1

Single Room 3

Nurse Station

250 500 1000 2000 4000

Figure 10.7 MLE-RT20 estimates for seven locations in the surgical ward, Bedford Hospital (day

time data) with 95% confidence limits

It appears that the results are consistent with the amount of absorbency provided by the ceiling, with

longer RTs estimated in those rooms with solid plaster ceilings or those with reflective ceiling tiles.


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212

10.5. Comparison of day and night time MLE-RT20 estimates

As discussed in Section 10.4.1, the data was segmented into day and night groups to allow for

comparisons to be made between times when acoustic conditions on the ward could potentially be

quite different. Day times are busy with visitors; there is a great deal of clinical and domestic activity;

and privacy curtains are often drawn around beds. All these events provide additional absorbency

which could affect the estimated MLE-RT20 values. Night time is a relatively quiet time, with minimal

disturbance by clinical staff, much less ward activity and hence lower additional absorbency. It could

therefore be assumed that the MLE-RT20 estimates would be longer at night than those during the

day, but further analysis of the results is required to establish this.

As expected, due to lower amounts of suitable data, the estimates calculated from the night time data

were much more variable. Many of the 95% confidence limits were found to be in excess of 0.1 s,

therefore the estimates were unusable and no comparisons could be made. However, there were

three instances where enough night time data with suitable decay phases existed. Figures 10.8, 10.9

and 10.10 show the comparisons between the day and night MLE-RT20 estimates in three different

patient bays in Addenbrooke’s and Bedford Hospitals.

.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Est

ima

ted

MLE

-RT

20

(s)

Octave Band (Hz)

Day time estimate 7-Bed Bay

Night time estimate 7-Bed Bay

250 500 1000 2000 4000


Addenbrooke’s Hospital


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213

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Est

ima

ted

MLE

-RT

20

(s)

Octave Band (Hz)

Day time estimate 12-Bed Bay

Night time estimate 12-Bed Bay

250 500 1000 2000 4000



0

0.1

0.2

0.3

0.4

0.5

0.6

250 500 1000 2000 4000

Est

ima

ted

MLE

-RT

20

(s)

Octave Band (Hz)

Day time estimate 4-bed bay

Night time estimate 4-bed bay

Figure 10.10 Comparison of day and night time estimates, 4-bed bay,

medical ward, Bedford Hospital

It can be seen from each figure, that the night time estimates are slightly higher than the day time, as

would be expected. However, the differences between the day and night time estimates for the seven

and 12-bed bays are very small, as little as 0.01 s at some frequencies. In the four bed bay, where

more data was available (12 days rather than seven), the MLE-RT20 estimate can be seen to be at


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214

least 0.05 s lower during the day in each octave band (with slightly larger differences found at lower

frequencies).

During a 24 hour period the acoustic conditions on a hospital ward are constantly changing due to

occupancy levels, opening and closing of privacy curtains, opening windows and many other aspects.

There is no easy way to record all of the conditions in the ward at a given time. It can therefore be

said that MLE-RT20 estimates are representative of snapshots of the acoustic conditions on the ward

when they are at their least reverberant. To explain this further, the MLE-RT20 method works by

searching the dataset for the fastest decaying region over a given four hour time window and hence

each estimate will be consistent with the highest occupancy / highest absorption on the ward.

Where night time estimates were available for comparison, they were found not to differ greatly from

the day time estimates, which indicates that the acoustic conditions on the wards were fairly stable at

all times.

10.6. Summary

The application of the MLE-RT20 method was investigated for use with discrete sound or trigger files

collected in occupied hospital wards. After rectifying initial audio quality issues, a number of validation

studies were carried out in simulated hospital wards. In each study, high trigger files (generated when

LAMAX exceeded 70 dB) were collected over a 60 minute period and a reverberation time estimate

(MLE-RT20) was calculated and compared with actual RT20 measurements made in the rooms using

an Impulse Response Method. Initial findings from the validation studies were positive, but highlighted

the need for sufficient data with uninterrupted reverberant decays, meaning significantly longer

recordings would be required.

The MLE-RT20 method was applied to data from noise measurements made in a number of ward

locations, at Bedford and Addenbrooke’s Hospitals. Each measurement interval was at least seven

days in length and the trigger files captured were segmented into day and night time groups. For each

data group, a day and night mean estimate was calculated for the entire measurement period.

For the day time MLE-RT20 estimations, in the octave bands 500 to 4000 Hz, the worst case 95%

confidence limits indicated a maximum error of ±0.08 s and as such the MLE-RT20 estimation method

can be said to demonstrate similar accuracy to standard measurement methods such as the Impulse

Response Method.

Night time MLE-RT20 estimations were found to be less accurate due to the availability of suitable

data, but it is felt that this could be further improved by longer measurement periods. Comparisons of

the night and day estimates provide an indication of the variation of acoustic conditions on the wards,

and were found not to differ greatly. This suggests that the acoustic conditions on the wards were

fairly stable at all times despite increased activity and occupancy levels.


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215

10.7. Conclusions

An estimation method which provides information regarding reverberation times in occupied spaces

has been trialled and has been shown to demonstrate similar accuracy to standard measurement

methods such as the Impulse Response Method.

The data provided by this method can usually only be generated using complex and time consuming

modelling techniques, and as such the MLE-RT20 method could be used to provide reverberation time

estimates in occupied areas where real time measurements are not practical or possible.

The following chapter presents some overall results from the main study; looking for general trends

and relationships within the objective and subjective data collected.

Acoustic Design for Inpatient Facilities in Hospitals Analysis of objective and subjective data

___________________________________________________________________________________________________________________

216

11. Analysis of objective and subjective data

11.1. Introduction

Analysis of the noise level data and questionnaire responses for each of the main study wards has

been carried out and presented in Chapters 7 and 9. This chapter aims to explore the overall results;

looking for general trends and relationships within the objective and subjective data collected from the

main study. Due to the differences in the care group, results from the pilot study are not considered in

this chapter.

The chapter begins by summarising the objective and subjective data collected in the study, as shown

in Table 11.1, which lists factors such as building age; ceiling types; ward configuration; measurement

durations and numbers of questionnaire responses.

The chapter continues by examining the objective data to investigate factors which might affect the

acoustic environment of a hospital ward. The physical aspects of the room design are considered and

relationships between noise levels and factors such as bay size are explored.

Patient perceptions are studied, with the effects of gender, age, hearing, length of stay and bed

position on noise annoyance and disturbance investigated. Aspects of privacy and speech

intelligibility are also examined.

The final part of this chapter considers staff perceptions of noise annoyance and interference with

work, and examines factors such as gender, age, and length of service.

11.2. Factors affecting noise levels

11.2.1. Effect of bay size

There is a general assumption among the acoustic, medical and architectural professions that the

larger the size of bay (that is the higher the number of patients in a bay), the greater the potential

noise level. In their 2004 paper on the role of the physical environment in the hospital of the 21st

Century, Ulrich et al (2004) state that ’a clear-cut finding in the literature is that noise levels are much

lower in single-bed than multi-bed rooms’. The data was therefore examined to see if this was found

to be the case in the current study.

Figure 11.1 shows the day time noise levels (LAeq,16hr) for each bay size, with the different study wards

represented by different bar colours. Interestingly, many of the noise levels measured in the single

rooms and three bed bays can be seen to be as high as those measured in the seven and twelve bed

bays. In fact the highest measured day time level is 60.6 dB LAeq,16hr which was measured in a single

room.

Table 11.1 Summary of the objective and subjective data collected during the study

Details

Hospital GOSH Addenbrooke's Addenbrooke's Addenbrooke's Bedford Bedford

Building Type PFI PFI 1970's tower Modular build Early 1980's build Early 1980's build

Age < 10 years < 10 years 50 years < 10 years 30 years 30 years

Ward Name Sky M4 D8 N3 Elizabeth Howard

Ward Type Surgical Surgical Trauma / Orthopaedics Respiratory care Medical Surgical

Ward capacity 18 32 35 25 30 26

Ward Config 2 x nurse stations;

3 x 4-bed bays;

6 x single rooms

2 x nurse stations;

5 x 4-bed bays;

12 x single rooms

1 x nurse station;

1 x 12-bed bays;

1 x 7-bed bay;

1 x 4-bed bay;

3 x 3-bed bays;

3 x single rooms

1 x nurse stations;

4 x 4-bed bays;

9 x single rooms

1 x nurse station;

3 x 6-bed bays;

2 x 4-bed bays;

4 x single rooms

1 x nurse station;

1 x 6 bed bays;

4 x 4 bed bays;

4 x single rooms

Ceiling tile type Acoustic in patient acc /

plaster in common areas

Acoustic throughout Metal pan with some

insulation

Acoustic throughout Acoustic throughout Acoustic throughout

Measurement: Location and length

Multi-bed bays 4 bed bay A - 10 days;

4 bed bay B - 5 days;

4 bed bay A - 6 days;

4 bed bay B - 8 days

3 bed bay A - 7 days;

3 bed bay B - 7 days;

4 bed bay - 8 days;

7 bed bay - 6 days;

12 bed bay - 2 non

consecutive 7 day

periods

4-bed bay A - 7 days;

4-bed bay B - 8 days;

4-bed bay C - 7 days

4-bed bay 1

(refurbished) -12 days

(over 2 non consecutive

weeks);

4-bed bay 2 - 7 days;


6-bed bay 4 - 8 days



4-bed bay 4 - 7 days

Single rooms Single room A - 5 days;

Single room B - 5 days

Single room A - 7 days;


Single room J - 7 days;

Single room K - 9 days

Single room A

(refurbished) - 5.5 days;


Single room A

(refurbished) - 7 days;


Nurse Stations Nurse station 1 - 10 days;

Nurse station 2 - 5 days

Nurse station 1 5 days;

Nurse station 2 - 7 days

Nurse station - 6 days Nurse station - 5 days Nurse station - 7 days;

Ward clerk's desk area -

7 days

Nurse station - 7 days

Questionnaires: Numbers of responses

Staff Quest reponse 12 10 20 11 18 7

Patient Quest response 31 14 47 13 40 42


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218

0

10

20

30

40

50

60

70

1 3 4 6 7 12

LAe

q,1

6h

r (d

B)

Bay size (number of patients)

■ Ward M4, Addenbrookes, ■ Ward N3, Addenbrookes, ■ Ward D8, Addenbrookes

■ Medical ward, Bedford, ■ Surgical ward, Bedford

Figure 11.1 Average day time levels by bay size for all main study wards

The relationship between the average day time noise level for each bay and bay size was

investigated, but this was not statistically significant (ρ=.038, ns).

Figure 11.2 shows average night time noise levels (LAeq,8hr) in each bay, grouped according to bay

size with the different study wards represented by different bar colours. It can be seen that some of

the highest average night time noise levels were measured in single rooms and three bed bays.

0

10

20

30

40

50

60

1 3 4 6 7 12

LAe

q,8

hr

(dB

)

Bay size (number of patients)

■ Ward M4, Addenbrookes, ■ Ward N3, Addenbrookes, ■ Ward D8, Addenbrookes

■ Medical ward, Bedford, ■ Surgical ward, Bedford

Figure 11.2 Average night time levels by bay size for all main study wards


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219

As with day time noise levels, the relationship between average night time noise levels for each bay

and bay size was not statistically significant (ρ= .014, ns).

11.2.2. Surgical and medical wards

The study has enabled the effect of ward type on noise levels to be examined.

At Bedford Hospital, two inpatient wards of similar layout were chosen in the main five storey ward

block. Both wards were subject to the same general hospital routines and regulations, but one ward

was a surgical ward, the other medical. This provided an opportunity for a comparison to be drawn

between the type of care provided and any differences this may have on the noise environment and

on patient and staff perceptions. More detailed discussion can be found in Chapter 7.

Overall noise levels at the nurse stations were found to be very similar between the wards, but the

content of the noise varied, with more frequent use of the nurse call and higher levels of staff

conversation captured at the surgical ward nurse station. Overall noise levels in the patient

accommodation were also found to be very similar between the wards, except for the bay directly

opposite the main nurse station in the medical ward, where instances of patients crying out and

increased clinical activities increased noise levels. This was specifically related to the numbers of

acutely ill elderly patients in this bay, many of whom were suffering from confusion or dementia.

Surgical and medical wards are very different in the type of services they provide. Surgical wards are

very busy with constant admissions for day or even half day procedures. Operations are booked in

advance and efficiency and timing are imperative. Medical wards are slower paced, with fewer

admissions and longer patient stays. These differences may in part explain the differences in

perceptions which are discussed in the following paragraphs.

Response to the questionnaire survey by staff in the surgical ward was poor, with only seven

completed questionnaires. It is possible that only those staff who felt strongly about noise made the

time to express their opinion. If this is the case, the results may be not wholly representative.

However, it is still worth comparing the staff perceptions between the wards.

Surgical ward staff rated visiting time, internal telephone, meal times, the nurse call, and trolleys as

interfering with their job much more highly than the staff on the medical ward. As this ward is more

fast paced, staff may find the presence of visitors, the constant ringing of the ward telephones and the

serving of meals impacts their efficiency further and hence causes more interference. The increased

use of the nurse call is reinforced by the results of the objective survey, but it is unknown why this is

used more on this ward. Trolleys are known to be used more extensively in the surgical ward with

patients constantly being wheeled through the ward to go to and from surgery and X-ray.

The major difference between patient perceptions was found to be the disturbance caused by patients

crying out at night in the medical ward. This was mainly due to the numbers of elderly patients on the


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220

ward, many of whom were suffering from confusion or dementia. As with the staff, patients also rated

trolleys and the nurse call more highly on the surgical ward. Other differences in perceptions were

due to maintenance issues on the ward or the lack of enforcement of hospital policy, but as such were

not an indication of the impact of the differences of care provided on the noise environment.

The three study wards at Addenbrooke’s Hospital were also a combination of surgical and medical

wards. However, these wards were not considered suitable for comparison due to the mixture of

different building design variables and care groups.

11.2.3. Impact of high level noise events on overall noise levels

Throughout this study, average day and night noise levels have been calculated for each bay, with

average hourly noise levels plotted over 24 hour intervals. Levels presented in these ways do provide

a general indication of the daily patterns of noise and overall levels measured in each bay, but fail to

illustrate the continuously fluctuating nature of the noise or provide any understanding of its content.

To help build up a more detailed picture of the noise climate, high level noise events (over 70 dB

LAmax) have been investigated and are reported in Chapters 7 and 9. This section examines the

impact of the numbers of high level noise events on the overall noise levels.

Figure 11.3 shows the average day time noise levels for each bay measured plotted against the

average number of day time high level noise events. It can be seen that the data points are a good fit

to the trend line suggesting a strong relationship between the average day time noise levels and

average numbers of high level noise events, confirmed by the statistically significant correlation

coefficient of ρ=.924 (p<0.01).

The gradient of the trend line shows that for every 100 high level noise events occurring during the

day time, there is an increase in the average LAeq,16hr of 1 dB.

y = 0.0101x + 49.88

0

10

20

30

40

50

60

70

0 200 400 600 800 1000 1200

LAe

q,1

6h

r (d

B)

Average number of high level noise events per day

Figure 11.3 Average day time noise levels and average number of day time high level

noise events for each bay


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221

Night time noise levels and high level noise events have been also examined to see if a similar

relationship exists. Figure 11.4 shows the average night time noise levels for each bay plotted against

the average number of night time high level noise events.

y = 0.0555x + 43.764

0

10

20

30

40

50

60

0 50 100 150 200 250

LAe

q,8

hr

(dB

)

Average number of high level noise events per night

Figure 11.4 Average night time noise levels and average number of night time

high level noise events for each bay

Although there is again a statistically significant relationship (ρ=.737, p<0.01) between noise levels

and the numbers of high level noise events, it is weaker for the night time than for the day time noise.

However, the gradient of the trend line is steeper than for the day time data and shows that for every

21 high level noise events occurring during the night time, there is an increase in the average LAeq,8hr

of 1 dB. This indicates that the effect of high level noise events on the overall noise levels (LAeq,8hr) is

greater at night than during the day and may suggest that these high level noise events cause greater

disturbance during the night. This is confirmed by the subjective responses of patients, where 52%

were disturbed by noise at night in contrast to 21% during the day (see Section 11.3.1).

11.2.4. Noise levels and reverberation times

As discussed in Chapter 10, reverberation times (RT) were estimated using the maximum likelihood

estimation method (MLE-RT20) for those bays with suitable data available. The relationship between

the daytime LAeq, 16hr and day time MLE-RT20 estimates has been investigated and is shown in Figure

11.5. There is a statistically significant correlation between the LAeq, 16hr and the RT, (ρ=.521, p<0.05),

with lower noise levels related to lower reverberation times as would be expected.

The gradient of the trend line shown in Figure 11.5 provides a relationship between the average day

time LAeq,16hr and RT, showing that for every 0.1 s decrease in the RT, there is a decrease in the

average day time noise level of 1.2 dB LAeq,16hr. This relationship is close to that found in the ceiling

intervention study discussed in Chapter 8, where the addition of an acoustically absorbent ceiling was


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222

found to decrease both RTs and overall noise levels. In this case, a 0.1 s decrease in RT

corresponded to a 1.8 dB reduction in noise level.

y = 12.471x + 50.15

0

10

20

30

40

50

60

70

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

LA

eq

,16

hr

(dB

)

MLE-RT20(secs)

Figure 11.5 Average day time noise levels and estimated reverberation times in each bay

11.3. Factors affecting patient perceptions of noise

Sources of noise annoyance and disturbance to patients were examined in detail in Chapters 7 and 9

in relation to each study ward. These sources were found to be ward specific and it would be

inappropriate to look for general trends in this data. This section aims to look at more general

relationships including whether gender, age, length of stay or bed position exacerbate feelings of

noise annoyance. Privacy, speech intelligibility and the effects of hearing impairment are also

examined.

11.3.1. Overall

Figure 11.6 shows the perception of day and night time noise for all 154 respondents. It can be seen

that the majority of respondents perceive the wards to be either quiet or a little noisy, both during the

day and at night. The more intense perceptions of ‘very noisy’ or ‘extremely’ noisy are chosen by very

few respondents.


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223

0

10

20

30

40

50

60

70

80

Very quiet Quiet A little noisy Noisy Extremely noisy

Nu

mb

er

of

resp

on

de

nts

Patient percepption of the noise climate

Day time perception

Night time perception

Figure 11.6 Overall patient perception of the noise climate

Figure 11.7 shows the percentages of all 154 respondents who indicated that they were annoyed by

day time noise and disturbed by noise at night. A relatively low percentage (21%) of patients felt

annoyed by noise during the day, but over half those patients questioned (52%) were disturbed by

noise at night.

0

10

20

30

40

50

60

Pe

rce

nta

ge

of

pa

tie

nts

(%

)

Annoyance Disturbance

Day time

Night time

Figure 11.7 Overall percentages of patient annoyed / disturbed by noise

Patients were also asked if they ever found it too quiet in the ward. Out of 154 respondents, only 9

patients said this was the case. Room data was only available for six of these respondents, with two

in a single room and four in either four or six bed bays.


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224

11.3.2. Patient gender

Figure 11.8 shows the mean perceptions of day and night time noise by male and female patients on

a scale of 1 to 5, where 1 indicates ‘very quiet’ and 5 indicates ‘extremely noisy’. It can be seen that

the average perception of day time noise is identical for both male and female patients (mean value of

2.5), however, male patients appear to perceive the wards to be noisier at night, whereas female

patients perceive the levels to be similar to those during the day. It should be noted that apart from

the average male perception of 3.5 at night (slightly noisy to noisy), the average ratings are around

2.5 (quiet to slightly noisy).

1

2

3

4

5

Male (n=92) Female (n=62)

Me

an

pe

rce

pti

on

of

no

ise

lev

el

(1=

ve

ry q

uie

t /

5=

ex

tre

me

ly n

ois

y)

Patient gender

Day time

Night time

Figure 11.8 Mean patient perception rating of noise by gender

Figure 11.9 shows the percentages of patients by gender that are annoyed or disturbed by day and

night time noise. It can be clearly seen that similar percentages of both male and female patients are

annoyed by noise during the day, which agrees with the perception of the noise climate during the day

as shown in Figure 11.8. However, it is interesting to note that during the night, slightly more women

(55%) than men (51%) are disturbed by noise. This is in contrast to the night time perception, as

shown in Figure 11.8, which shows that women perceive the ward to be quieter at night than men.

0

20

40

60

80

100

Male (n=92) Female (n=62)

Pe

rce

nta

ge

s o

f p

ati

en

ts a

nn

oy

ed

/ d

istu

rbe

d (

%)

Patient gender

Day time annoyance


Figure 11.9 Percentages of patients annoyed / disturbed by noise by gender


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225

11.3.3. Age

This section examines the effects of age on patient perceptions of noise, and on annoyance and

disturbance. Figure 11.10 shows that perceptions of day time noise are found to be very consistent

across all age ranges, with mean values between 2.4 and 2.6, suggesting that patients of all ages

gauge the noise climate to be in the range ‘quiet’ to ‘slightly noisy’ during the day. However, the

perception of noise at night appears to be more variable, with two age groups perceiving slightly

noisier conditions: the under 20’s (mean value 2.8); and those in the 41-50 age group (mean value of

3.1). Patients in the age groups 31-40, 51-60 and 60+ appeared to perceive the conditions similarly,

with those in the 20-30 age bracket perceiving the wards at night to be the quietest (mean value of

1.9). It can also be seen that the perception of noise on the ward during the night is generally lower

than it is during the day, except in age groups under 20 and 41-50 years.

1

2

3

4

5

<20 20-30 31-40 41-50 51-60 60+

Me

an

pe

rce

pti

on

of

no

ise

lev

el

(1=

ve

ry q

uie

t /

5=

ex

tre

me

ly n

ois

y)

Age group (years)

Day time

Night time

(n=8)(n=16)

(n=19)

(n=22)

(n=84)

Figure 11.10 Mean rating of patient perceptions of day and night noise and age

Noise annoyance / disturbance and age group is shown in Figure 11.11. It can be clearly seen that

patients in the age groups 31-40 and above are more disturbed by noise at night than during the day;

which is in contrast to many of the perceptions shown in Figure 11.10. Patients in the 41-50 age

group appear to be more disturbed by night time noise than those in any other age group (74%),

followed by the 51-60 age group (61%). This could be due to independent lives led by the individuals

in these groups and levels of control they are used to having within their lives.

(n=5)


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226

0

20

40

60

80

100

<20 20-30 31-40 41-50 51-60 60+

Pe

rce

nta

ge

s o

f p

ati

en

ts a

nn

oy

ed

/ d

istu

rbe

d (

%)

Age group (years)

Day time

Night time

(n=8)

(n=16)

(n=19)

(n=22)

(n=84)

(n=5)

Figure 11.11 Percentages of patients annoyed / disturbed and age

11.3.4. Hearing impairment

26% of respondents indicated that they suffered from a hearing impairment of some kind. This could

include many different conditions such as hearing loss; increased sensitivity at particular frequencies

and tinnitus. Figure 11.12 shows the breakdown of hearing impairment by patient age. It can be seen

that out of those suffering from some type of hearing impairment, 75% are over years 60 years of age.

This may account for the lower perceptions of the noise climate by this age group (shown in Figure

11.10)

0

10

20

30

40

50

60

70

80

<20 20-30 31-40 41-50 51-60 60+

Pe

rce

nta

ge

of

he

ari

ng

im

pa

ire

d (

%)

Age group (years)

Figure 11.12 Percentage of hearing impaired by age group


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To see if hearing impaired patients were any less annoyed or disturbed by noise, percentages of

annoyance and disturbance are plotted against hearing impaired / non hearing impaired patients, as

shown in Figure 11.13. In terms of annoyance 7% fewer hearing impaired patients indicated they

were annoyed by day time noise than the non hearing impaired, with 3% fewer patients indicating that

they were disturbed at night.

0

20

40

60

80

100

Hearing impaired No impairment

Pe

rce

nta

ge

of

pa

tie

nts

an

no

ye

d /

dis

turb

ed

(%

)

Day time annoyance


Figure 11.13 Percentage of patients annoyed / disturbed with hearing impairment

Speech intelligibility and perception of speech privacy were also examined for differences between

the hearing impaired patients and non hearing impaired. In terms of speech intelligibility, 35% of

hearing impaired patients felt they could not always hear when staff spoke to them, in contrast to 82%

of patients without any impairment. Little difference was found in terms of conversational privacy, with

69% of patients with a hearing impairment feeling that they could carry out a private conversation on

the ward, and 65% of those without a hearing impairment feeling the same.

11.3.5. Length of stay

Length of patient stay has been investigated to see whether there is a difference in perceptions of

noise and annoyance and disturbance between short term and longer term patients. Figure 11.14

shows mean perceptions of day and night time noise for patients who have been in hospital for less

than 1 week, between 1 and 3 weeks and for more than three weeks. Responses are very consistent

for patients who have been on the ward for up to three weeks. Longer term patients, however, appear

to perceive day time noise levels very slightly higher and night time noise levels slightly lower.

Perhaps this in an indication that longer term patients manage to acclimatise to the noise of the ward

at night. However, it should be noted that the sample size for patients who had been on the ward for

over three weeks was comparatively small (n=14).


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228

1

2

3

4

5

< 1 week 1 - 3 weeks > 3 weeks

Me

an

pe

rce

pti

on

of

no

ise

lev

el

(1=

ve

ry q

uie

t /

5=

ex

tre

me

ly n

ois

y)

Length of patient stay

Day time

Night time

(n = 96)(n = 44)

(n = 14)

Figure 11.14 Mean rating of patient perceptions of day and night noise and length of stay

Figure 11.15 shows the percentages of patients annoyed / disturbed by noise in relation to length of

stay. It can be seen that 20% of patients who had been on the ward for less than one week, and 19%

of patients whose stay was one to three weeks indicated they were annoyed by day time noise.

However, this percentage more than doubled for longer term patients, with 43% annoyed by noise

during the day. This trend was reversed for night time disturbance, with only 36% percent of long term

patients expressing night time disturbance in comparison to those patients who had been on the ward

for less time. Again, as with the noise perception, this response suggests a certain amount of

acclimatisation to the night time noise climate by longer term patients, but more sensitivity to noise

during the day.

0

20

40

60

80

100

< 1 week 1 - 3 weeks > 3 weeks

Pe

rce

nta

ge

of

pa

tie

nts

an

no

ye

d /

dis

turb

ed

(%

)

Length of patient stay

Day time annoyance


Figure 11.15 Percentages of patients annoyed / disturbed and length of stay


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229

11.3.6. Bed position

In general beds are only specifically allocated to either infectious patients who require barrier nursing

(these patients may be placed in a single room); on the basis of gender (if no same sex

accommodation is available patients may be placed in a single room); or if the patient is very unwell

and requires observation (the patient may be placed in the bay nearest to the nurse station).

This section investigates whether there are any relationships between noise annoyance / disturbance

and bed position, with positions defined as ‘next to the ward corridor’, ‘in the centre of the bay’, ‘by the

window’, or in ‘a single patient room’. Figure 11.16 shows the percentages of patients annoyed /

disturbed in each type of bed location. It can be seen that surprisingly, the highest percentages of

patients reporting daytime annoyance and night time disturbance are those staying in single rooms,

with 50% and 58% reporting annoyance and disturbance respectively. Percentages of patients in

multi-bed bays reporting daytime annoyance are much lower, between 17% and 24%, with those by

the window reporting slightly lower levels of annoyance. Percentages of patients reporting night time

disturbance are similar in all cases except for those patients in beds by the window, where 10% fewer

respondents report disturbance.

It is interesting that the lowest levels of annoyance / disturbance are reported by patients in beds

located by windows. This is a similar finding to that by Yildirim et al (2007), who observed that for

office workers, being positioned by a window compensated for some of the negative perceptions of

open plan offices, such as low levels of visual or acoustic privacy.

0

20

40

60

80

100

Corridor Window Middle Single room

Pe

rce

nta

ge

of

pa

tie

nts

an

no

ye

d /

dis

turb

ed

(%

)

Bed position on ward

Daytime annoyance


(n=9)

(n=54)

(n=12)(n=18)

Figure 11.16 Percentages of patients annoyed / disturbed and bed position


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230

11.3.7. Speech intelligibility and privacy

Speech intelligibility on the wards is extremely important to enable clinical staff and patients to be able

to discuss issues surrounding the patient’s condition and their treatment without the loss of important

information. Speech intelligibility was not measured objectively during this study, but was gauged in

part by asking patients if they could always hear clearly when the doctors and nurses spoke to them,

which overall 69% of respondents said that they could. The relationship between speech intelligibility

and the size of the bay was investigated by averaging the number of people who said they could

always hear clearly. No relationship between was found, with a low correlation coefficient (ρ=.333,

ns). The perceptions of speech intelligibility among hearing impaired patients was also investigated

and discussed in Section 11.3.4.

In recent times there has been much publicity surrounding poor conversational privacy on hospital

wards. To investigate this, patients were asked if they felt able to hold a private conversation with

clinicians at their bedside. The responses in relation to the bay size are shown in Figure 11.17. It can

be seen that 100% of patients in single rooms felt that they could hold private conversations. This is

unsurprising as these patients have the option to close the door to their room if necessary. Between

60% and 68% of patients on wards with four or more beds felt that they could hold private

conversations, with only 40% of patients in three bed bays feeling they could. The relationship

between conversational privacy and the size of the bay was investigated by averaging the number of

people who found conversational privacy to be acceptable. There was not a significant correlation

found between ward size and conversational privacy (ρ= -.322, ns).

0

20

40

60

80

100

1 3 4 6 7 12

Pe

rce

nta

ge

of

pa

tie

nts

wh

o f

elt

th

ey

co

uld

ho

ld a

pri

va

te

con

ve

rsta

ion

(%

)

Bay size (number of beds)

Figure 11.17 Patient privacy and bay size


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11.4. Factors affecting staff perceptions of noise

This section considers the responses of staff on the main study wards in Bedford and Addenbrooke’s

Hospital. Sources of noise annoyance and interference to staff were examined in detail in Chapters 7

and 9 in relation to each study ward. As with patient perception, these sources were found to be ward

specific and so to look for general trends in this data would not be appropriate. This section looks

further at more general relationships including whether gender, age, and length of service increase

feelings of noise annoyance and noise interference in relation to work.

11.4.1. Overall

Figure 11.18 shows the perceptions of day and night time noise for all 66 staff respondents. It can be

seen that the highest percentage of staff (25%) cite levels of annoyance and interference as ‘slight’,

with 18% moderately annoyed by noise. Higher levels of annoyance are cited by only nine staff in

total (13%), with eight choosing ‘very noisy’ and one selecting ‘extremely’.

0

5

10

15

20

25

30

Not at all Slightly Moderately Very much Extremely

Pe

rce

nta

ge

of

sta

ff (

%)

Staff annoyance and interfernce levels

Annoyance

Interference

Figure 11.18 Staff levels of annoyance and interference

11.4.2. Gender

Figure 11.19 shows the average feeling of noise annoyance and noise interference with work by staff

gender. It can be seen that the average level of annoyance and interference on the ward is higher for

male staff, however all ratings are fairly low in the range ‘slightly’ to ‘moderately’ for both men and

women. Noise annoyance is rated consistently higher than interference with work by both male and

female staff.


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1

2

3

4

5

Male Female

Lev

el o

f n

ois

e a

nn

oy

an

ce /

inte

rfe

ren

ce

(1=

no

t a

t a

ll /

5=

ex

tre

me

ly)

Staff gender

Noise annoyance

Noise interference

(n=13)

(n=54)

Figure 11.19 Level of noise annoyance / interference by staff gender

11.4.3. Age

The next section considers whether the age of the staff member is related to the level of noise

annoyance / interference they perceive in their working environment.

1

2

3

4

5

<20 20-30 31-40 41-50 51-60

Lev

el o

f n

ois

e a

nn

oy

an

ce /

inte

rfe

ren

ce

(1=

no

t a

t a

ll /

5=

ex

tre

me

ly)

Age group (years)

Noise annoyance

Noise interference

(n=11)

(n=3)

Figure 11.20 Level of noise annoyance / interference by staff age

It can be seen in Figure 11.20 that it is the younger members of the staff and the older staff who

appear to have more extreme views. Staff under 20 years old appear to be untroubled by noise while

(n=3)

(n=34)

(n=16)


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233

those in the 51-60 age group rate noise annoyance and interference more highly than any other age

group (with a mean of 3.0 for both annoyance and interference). However, it should be noted that the

sample sizes for both these age groups are very low (n=3). Statistically, no relationship was found

between levels of annoyance and age (ρ= -.262, ns), or levels of interference and age (ρ= -.16, ns).

11.4.4. Time worked on the ward

The relationship between length of time worked on the ward and level of noise annoyance / noise

interference is illustrated in Figure 11.21. It can be seen that in all cases the feelings of annoyance

and interference are fairly low, predominantly in the range ‘slightly’ to ‘moderately’, with both new staff

and staff in the 4-5 year bracket reporting very low levels. Although ratings increase for the first three

years, this is not a constant trend overall. One interesting point to note is that staff who have worked

on the ward for over five years rate interference with work more highly than annoyance, in contrast to

all the other time brackets.

1

2

3

4

5

<1 year 1-2 years 2-3 years 3-4 years 4-5 years 5+ years

Lev

elo

f n

ois

e a

nn

oy

an

ce /

inte

rfe

ren

ce

(1=

no

t a

t a

ll /

5=

ex

tre

me

ly)

Time worked on the ward

Noise annoyance

Noise interference

(n=30)

(n=8)(n=9) (n=4)

(n=3)

(n=11)

Figure 11.21 Level of noise annoyance / interference by time worked on the ward

No statistically significant relationship exists between time worked on the ward and annoyance ratings

(ρ=.16, ns), and time worked on the ward and interference ratings (ρ=.29, ns).

11.4.5. Time worked at the hospital

The relationship between length of time worked at the hospital and levels of noise annoyance / noise

interference is illustrated in Figure 11.22. It can be seen that in most cases the feelings of annoyance

and interference are fairly low, predominantly in the range ‘slightly’ to ‘moderately’, with those new

staff and staff in the 3-4 and 4-5 year brackets reporting very low levels. Although levels increase for

the first three years, this is not a constant trend overall. As with time worked on the ward, staff who


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234

have worked in the hospital for over five years rate interference with work more highly than

annoyance; in this case in the ‘moderately’ to ‘very much’ range.

Statistically, there is no significant relationship between time worked at the hospital and annoyance

and interference ratings (ρ= .16, ns and ρ= .29, ns respectively).

1

2

3

4

5

<1 year 1-2 years 2-3 years 3-4 years 4-5 years 5+ years

Lev

el o

f n

ois

e a

nn

oy

an

ce /

inte

rfe

ren

ce

(1=

no

t a

t a

ll /

5=

ex

tre

me

ly)

Time worked at the hospital

Noise annoyance

Noise interference

(n=21)(n=9)

(n=7)

(n=3)

(n=24)

Figure 11.22 Level of noise annoyance / interference by time worked at the hospital

11.4.6. Relationship between noise annoyance and noise interference

Considering the overall data set of 66 responses, the relationship between noise annoyance and

noise interference was investigated. A statistically significant correlation between annoyance and

interference ratings was found (ρ= .730, p=0.01). This suggests that staff rating noise annoyance

highly will also rate noise interference highly. If this is the case, it is possible that posing a single

question on noise annoyance / interference would be sufficient to provide the information required.

11.5. Discussion

Analysis of the overall dataset on noise and patient and staff perceptions has yielded some interesting

and surprising results.

It has been shown that the size of a bay is not related to the noise levels in the bay during the day or

at night, with some of the highest levels measured in single rooms and in three and four bed bays.

Overall measured noise levels in a medical and surgical ward at the same hospital were found to be

similar; however the content of the noise and the perceptions of the staff and patients differed. In the

busier surgical ward, visiting time, the internal telephone, meal times, the nurse call, and trolleys were

(n=2)


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235

all found to cause more interference to the work of the staff. Patients on the medical ward found the

crying out of other patients caused a great deal of annoyance and disturbance, whereas patients on

the surgical ward rated trolleys and the nurse call more highly.

The average number of high level noise events (greater than 70 dB LAmax) were shown to be strongly

correlated to overall measured noise levels both day and night. Analysis suggests that the impact of

high level noise events on night time levels is considerably greater than during the day, as the

increase of day time ambient levels provide a certain amount of masking. This suggests that patients

would experience greater disturbance by high level noise events during the night.

Noise levels have been shown to be directly related to RT, with lower noise levels corresponding to

lower RTs, as expected. Analysis has found that for every 0.1 s decrease in the RT, there is a

decrease in the average day time noise levels of 1.2 dB LAeq,16hr . This confirms the relationship that is

illustrated by the ceiling intervention study in Chapter 8, where the addition of an acoustically

absorbent ceiling was found to decrease both RTs and overall noise levels.

The perception of the noise climate by male and female patients was found to differ, with male

patients perceiving a noisier environment during the night than female patients. However, annoyance

and disturbance ratings were the same for both genders.

Patients whose stay on the ward was less than three weeks perceived the noise climate on the ward

to be similar both day and night, however they were more disturbed by night time noise than longer

term patients (> 3 weeks). However, longer term patients appeared to be more annoyed by day time

noise than shorter term patients but were less sensitive to noise during the night. This suggests a

certain amount of acclimatisation to noise on the ward at night.

Differences in noise perception and annoyance were found between patient age groups. In terms of

perception, day and night levels were generally perceived similarly and were fairly low, in the ‘quiet’ to

‘slightly noisy’ category, with patients in the 41-50 age group at night time having the worst

perceptions of the noise environment, with an average rating of 3.2. In terms of annoyance and

disturbance it was found that patients in the age groups 31-40 and above were much more disturbed

by noise at night than during the day, with the highest percentage again in the 41-50 age group

(74%). Perhaps this is an indication of the higher expectations of those patients in this particular age

bracket.

Patients staying in a single room were found to be more annoyed by noise than those in multi-bed

bays, with 50% and 58% of single room patients reporting day time annoyance and night time

disturbance respectively. Day and night time levels reported by patients in a multi-bed bay were

found to be considerably lower during the day (20%) and slightly lower at night (53%). It was found

that patients in beds situated by the window reported lower rates of day time annoyance and night

time disturbance (17% and 47% respectively) than patients in other bed locations.


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236

Satisfactory conversational privacy was reported by all patients in single rooms, and by similar

percentages, 63% on average, of those in bays of four to twelve beds. Interestingly only 40% of

patients in three bed bays felt that they could speak privately.

Little difference was found in terms of noise annoyance and disturbance and conversational privacy

between those patients with a hearing impairment and those without.

Levels of noise annoyance and interference rated by staff were generally found to be low, in the most

part in the ‘slightly’ to ‘moderately’ range. In terms of staff gender, male staff rated noise annoyance

and interference slightly higher than female staff and in relation to age, the youngest members of the

staff and the older staff had more extreme views. Staff under 20 years old appeared to be untroubled

by noise, with those in the 51-60 age group rating noise annoyance and interference more highly than

any other age group. However, even in this case it must be stressed that the mean rating of 3.0 is not

particularly severe.

No significant relationship was found between staff attitudes to noise and either the length of time

they had worked on the ward or the length of time they had worked at the hospital. The main

difference was in the ‘5+ years’ bracket in both categories, where staff rated noise interference with

work more highly than noise annoyance. Perhaps this is related to the changes that these staff have

seen over many years in relation to additional noise sources, for example, the more prevalent use of

ward equipment with alarms, and it may be an indication of the worsening noise climate in hospitals.

11.6. Conclusions

The main conclusion of this chapter is that, contrary to current thinking, single bed rooms are not

quieter than multi-bed bays. This has been shown both objectively, from the measured noise level

data, and subjectively from patient perceptions of noise. This is an important finding given the current

thinking and the preference for providing more single rooms in hospital wards.

The results also highlight the need to reduce RTs in hospital wards in order to decrease the overall

noise levels.

Other points to note are that there is some evidence that longer term patients acclimatise to noise at

night, but become more annoyed by noise during the day time; and that consideration needs to be

given to the issue of speech privacy and how it may be improved, particularly in 3-bed bays.

The following chapter looks at ways of controlling hospital noise using a multi-faceted approach. The

validity of relevant standards is discussed and acoustic reporting metrics are also explored.

Acoustic Design for Inpatient Facilities in Hospitals Noise control in inpatient care

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12. Noise control in inpatient care

12.1. Introduction

This study has shown that the problem of hospital noise is very complex in nature, with many different

factors affecting the noise climate. This was also found to be the case in the previous research on this

topic. It is felt that if any significant improvement is to be achieved, a multi-faceted approach is

required, which should be centred on three main areas:

� Optimising the acoustic design of the ward

� Minimising the disturbance caused by equipment in use on the ward

� Modifying the behaviour of those on the ward

This chapter discusses each of these areas in detail in relation to the findings from the current study.

Validity of relevant standards and reporting metrics are also explored.

12.2. Optimising the acoustic design of the ward

This study focuses on a number of areas of acoustic design, including whether the design for infection

control purposes has compromised ward acoustics; the effects of adding acoustic absorbency; and

the impact of the ward design and building construction on the noise climate. These areas are

considered and discussed further in the following section.

12.2.1. Design for infection control

One of the aims of the study was to investigate whether the design of a hospital building for infection

control purposes was detrimental to the acoustic design. Three of the study wards which were built in

the last decade, a time when concerns over infection control were being considered carefully in terms

of building finishes. The study found that in each of the wards, suspended ceilings with good quality

acoustic tiles were installed throughout all patient accommodation, and in some instances in the

common areas. Reverberation times in all the areas with acoustic tiles were found to be very low.

The use of acoustic tiles in these new buildings is largely due to the efforts of the acoustic product

manufacturers, who have responded positively to infection control concerns by developing a number

of different ceiling tiles specifically for use in healthcare buildings, and thus ensuring that the acoustic

design of the wards is not compromised. Tiles are now available which can withstand cleaning using

strong disinfectants, or even steam cleaning. Specific tiles have even been produced that are treated

with antimicrobial agents, preventing any bacteria from growing on their surface.


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12.2.2. The effects of adding acoustic absorbency

The latest acoustic design guidance, HTM 08-01: Acoustics (The Stationary Office, 2008), suggests

that the most appropriate area for acoustically absorbent material should be a ceiling, with the

minimum absorption area equivalent to 80%. The beneficial effects of installing an acoustic ceiling are

illustrated by the ceiling intervention study, which was discussed in Chapter 8, and showed a

reduction of 0.15 s in reverberation time (RT) and 2.4 dB in noise level.

The relationship between RT and noise levels is discussed further in Section 11.2.3, which shows a

statistically significant relationship between day time RT estimates and daytime LAeq,16hr (ρ=.498,

p<0.05). It is shown that for every 0.1 s decrease in the RT, there is a decrease in the average day

time noise levels of 1.2 dB LAeq,16hr. This is reasonably consistent with the findings of the ceiling

intervention study.

These findings stress the importance of installing an acoustically absorbent ceiling in hospital wards.

12.2.3. Ward design

The five main study wards were all designed around a long central corridor, with patient

accommodation generally situated on one side, and healthcare resources on the other. The pilot

study ward was based on a ‘racetrack design’ with patient accommodation situated on the outside of

the building, and healthcare resources in the centre. Objective and subjective data from the study

suggests that the most important aspect to be considered in terms of ward layout is not the overall

design, but the positioning of patient accommodation in relation to the healthcare utilities. Careful

thought must be given to ensure that there are no direct sound paths from potentially noisy areas to

patient accommodation. The two study wards in Bedford Hospital provide several examples of where

poor positioning of patient accommodation leads to annoyance and disturbance of patients, and are

discussed below.

� The kitchen, ward clerk’s desk and staff room are all situated directly opposite a multi-bed bay

in the two study wards. All these areas are potentially noisy, with bangs and crashes often

heard from the kitchen area, and conversational noise heard from the staff room and at the

ward clerk’s desk. Objective and subjective results both indicate that noise from these areas

has a detrimental effect in terms of noise levels and patient annoyance and disturbance in the

bay opposite.

� Two single rooms are positioned directly behind the main nurse station in both wards.

Objective and subjective results again indicate that patients in these rooms are adversely

affected by noise from activity at the nurse station: with staff conversation; the nurse call; and

general activity clearly audible.

Not only is thought required in the siting of patient accommodation, but care must also be taken in

ensuring that areas that require easy access by staff are designed as such. One particular example of


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239

impractical design is found in Ward N3 at Addenbrooke’s Hospital. Here, a number of rooms are

situated close to the nurse station, including the clean and dirty utility rooms, and a general

storeroom. None of these rooms contain anything requiring secure storage, but for some reason all

doors to these rooms have been fitted with security access via a key code pad. Staff entering these

rooms often have their hands full, and so to overcome the need to input the security code, the doors

to these rooms are all left on the latch. Unfortunately, this has a negative impact on the noise

environment as the doors literally bounce when shutting, causing a loud bang. In fact this noise

accounted for 48% of the total number of trigger files captured during the measurement period in this

location, with levels consistently measured at 79 dB LAmax.

One issue highlighted by the study is that of ‘open door nursing’, which is still used by clinicians in UK

hospitals today. The study found that the staff have been trained to carry out their nursing duties with

doors to the patient bays and single rooms left open at all times for observation purposes. The only

exception to this is if barrier nursing is required, and then doors to a single room may be closed.

Several sections in the latest acoustic healthcare design guidance HTM 08-01 (The Stationary Office,

2008) advise on levels of noise attenuation between rooms, and of the type and properties of suitable

acoustic doors to be installed on the wards. It is considered extremely important that an

understanding of the way the building will be used when occupied is considered when specifying the

acoustic design. Considerable expense may be incurred in relation to the installation of acoustic doors

and sound attenuating material, when in reality they will be of no actual benefit, as the staff will leave

the doors to the patient accommodation open.

12.2.4. Building construction

The majority of the ward buildings in this study are primarily of concrete construction, with concrete

floors, suspended ceilings, and stud or block partitions. As this study is concerned with occupied

buildings, it has not been possible to view the building construction as a singular entity. However,

subjective responses have provided clues as to areas within the building construction that may cause

annoyance to staff and patients. These areas are discussed below.

� The mechanical ventilation system was cited by ward staff in Sky Ward, GOSH. The installed

system is centrally controlled, but air flow was found to be noticeably different in some areas

of the ward, with some patient accommodation and staff offices adversely affected by noise

and heat from the system.

� At Bedford Hospital, where wards are naturally ventilated, annoyance and disturbance to

patients due to external noise increased during the summer months, when the windows were

open, with 37% of patients citing external noise as a night time disturbance. This appeared to

be a less of problem in the cooler months, with lower percentages of patients (13%)

disturbed.


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� Single glazing also accounted for additional disturbance by external noise, as discussed in

Section 7.9.2. However, it is interesting to note that patient opinions were split, with some

finding the lack of attenuation by the single glazed unit to be annoying, but with others finding

the connection with the outside world beneficial.

Careful consideration needs to be given to the choice of mechanical and / or natural ventilation, as

both have their own inherent problems.

One study ward is of a very different construction and this is worth discussing in further detail. Ward

N3 is a modular ward at Addenbrooke’s Hospital and is of mainly timber construction. This block was

opened in 2009 and was built to comply with acoustic standard HTM 2045. It has a good quality

acoustic ceiling and all room partitions are sound insulated, but it is the floor that is of interest. When

the ward first opened, the springy nature of this floor generated many complaints from staff, who

found it detrimental to their feet. Remedial work was carried out to further stiffen the floor, and

although improved, the floor does appear to have a negative effect on the noise climate, by

magnifying certain sounds. Groups of people walking past the nurse station were found to generate

noise levels exceeding 70 dB LAmax, a footfall noise level not found on any other study wards. This

was confirmed by questionnaire responses, where 40% of ward staff claimed they found the sound of

footsteps annoying, and 20% of patients cited footsteps as a night time disturbance. These

percentages are the highest found in relation to annoyance and disturbance from footsteps on any

study ward. The noise of trolleys also appears to be exacerbated by the timber floor construction, with

40% of patients citing trolleys as a source of annoyance.

Care should be taken when choosing the type of floor construction for use in hospital wards, as the

use of a timber floor can exacerbate noise levels and is found by staff cause discomfort.

12.2.5. Building age and overall noise levels

The age of the hospital buildings included in the study varied from less than ten years to around 40

years, with some new build (within the past ten years) and others built in the 1970’s and 1980’s. The

1970’s ward lacked space, having a larger number of beds than it was originally designed for (as

discussed in Chapter 9.3.1) and the largest bay sizes of all the study wards. Occupied RTs were

found to be slightly higher than the newer wards with acoustic ceilings, but these values were still

relatively low (ranging from 0.4 s to 0.6 s at 1 kHz). The 1980’s wards were single glazed, which

accounted for additional disturbance by external noise, as discussed in the previous section. The

positioning of patient accommodation in relation to the kitchen, ward clerk’s desk and nurse station

was also found to be detrimental to noise levels. Buildings constructed in the last ten years were

found to have good quality acoustic ceilings and very low reverberation times (for example, less than

0.3 s at 1 kHz in Ward N3). Wards were generally found to be much more spacious, with wider

corridors, plenty of equipment storage and improved bed spacing.


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Figure 12.1 shows the day time noise levels (LAeq,16hr) measured in the patient accommodation

grouped by building age. It can be seen that with only one exception, overall measured LAeq,16hr values

lie within a 10 dB band, between 50 and 60 dB LAeq,16hr. A statistically significant correlation was found

between building age and overall day time noise levels (ρ= -.589, p=0.01), suggesting that newer

buildings are quieter.

0

10

20

30

40

50

60

70

1970's 1980's 2000's

LA

eq

, 16h

r (d

B)

Decade in which building comissioned

Figure 12.1 Average day time levels by building age for all patient accommodation

Figure 12.2 shows the night time noise levels (LAeq,8hr) measured in the patient accommodation

grouped by building age. It can be seen that all overall measured LAeq,8hr values lie within a 10 dB

band, between 41 and 51 dB LAeq,8hr. In the case of night time noise levels and building age no

significant relationship was found (ρ= -.348, ns). However, the negative correlation coefficient

indicates a trend for the overall noise levels to decrease in the newer buildings as with the daytime

levels.

0

10

20

30

40

50

60

70

1970's 1980's 2000's

LA

eq

, 8h

r (d

B)

Decade in which building commissioned

Figure 12.2 Average night time levels by building age for all patient accommodation


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12.3. Ward equipment

The study shows that the cacophony of alarms and tones emitted by the electronic equipment in use

on the ward is becoming a major source of noise. Items such as nurse call systems, internal

telephones and medical equipment occur frequently and were found to generate high noise levels,

with some alarms left for some time before they are reset. These types of systems are continually

cited by staff and patients as sources of annoyance and disturbance.

The poor design and maintenance of other types of ward equipment is also found to contribute to high

levels of noise, and is discussed further in this section, with possible noise control measures

suggested where appropriate.

Following the pilot study carried out at GOSH, follow up meetings were held with staff to discuss the

results of the study and possible improvements that could be made to the noise environment. Where

appropriate the feedback from these meetings is incorporated into the following sections.

12.3.1. Nurse call systems

In preliminary discussion with ward managers, the nurse call was cited as a source of annoyance, and

this was supported by the questionnaire responses from staff on all the study wards. In some

instances annoyance was related to correspondingly high noise levels, for example a level of 72.7 dB

LAmax was measured at the nurse station in the surgical ward at Bedford Hospital.

Some of the nurse call annoyance was due to the level of the noise emitted by the system. In several

cases it was found that the day and night volume settings, which were meant to change the volume

level, appeared to be faulty, with no difference found in the volume of the tone emitted. In other cases

the volume was simply too loud and not adjustable. Unfortunately, although annoying this did not get

logged as no clear reporting structure appeared to be available for issues of this nature.

Commissioning of the system also appeared to be at fault on occasion, with staff finding that the

system was not performing as they would wish in terms of functionality. Staff in one particular study

ward commented that they were not able to hear the nurse call if they were attending to a patient in a

different bay, and this made it hard to carry out their nursing duties effectively.

12.3.2. Internal telephones

As with the nurse call system, the internal telephone was cited as a source of annoyance and

interference by staff, and as a disturbance by patients. Comments made suggest that one of the main

issues is not about the volume of the ring tone, but the length of time the phone rings before being

answered.

In all study wards there are a number of wired, static phones on desks. In some cases these are used

alongside personal paging systems. Given that the majority of people own mobile telephones which


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have silent, vibrating functionality, surely the ringing desk phone is an unnecessary object in any

hospital ward?

In a post study meeting with staff from the pilot study ward at GOSH, a number of interesting points

were made regarding telephone use on the ward. These are detailed below.

� The responsibility of the ward clerk on this ward is to act as a first point of contact for external

telephone calls. When away from her desk, which is a regular occurrence, unanswered

telephone calls are redirected through to the ward to be answered by a member of the clinical

staff. This of course wastes the clinicians’ time, as they then have to take a message back to

the ward clerk’s desk. It was suggested that by simply installing a voice mail system many of

these unnecessary calls could be dealt with automatically. This idea was positively received

by all staff and has been implemented.

� Some newer staff members commented that they were not aware of how to turn down volume

levels of the telephone ring tones. This suggested a possible issue with the training of new

staff.

� A new CISCO system is currently being trialled in another ward at GOSH which uses internet

technologies. The system uses wireless telephones which are given to each member of staff

and could potentially replace all existing telephones and paging systems, and the nurse call.

Staff felt that if implemented, this system would be beneficial.

12.3.3. Medical equipment alarms

Medical equipment alarms were also one of the major sources of annoyance to both staff and

patients, with the alarms emitted often loud, and on occasion seemingly unnecessary. One example

captured during the study was that of a patient monitor which bleeped at a level of 75 dB LAmax every

30 seconds for two and a half hours in a single room. This would surely have disturbed the patient,

who would have been trying to rest, and must surely warrant the question: if this did not require

intervention, then why was there a tone emitted at all?

It is possible that the setup of many pieces of medical equipment is so complex that once they are

commissioned, the settings are never changed. For example, one particular ECG machine identified

had a total of 16 different settings. Again this suggests that there should be some collaboration

between the staff who use these pieces of equipment and the installer and / or manufacturer.

Continued staff training may also be an issue. It is possible that when first installed, staff on the ward

are provided with the necessary training on how to tailor a piece of medical equipment to their own

requirements. However, with the extremely high turnover of staff in healthcare and the regular use of

temporary agency staff, this knowledge may be lost relatively quickly. Perhaps follow on training

should be provided periodically, or staff should be issued with necessary information on induction.


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12.3.4. Doorbell

The pilot study ward at GOSH and each study ward at Addenbrooke’s Hospital could only be

accessed using a security pass. For visitors to announce their arrival at the ward entrance, a doorbell

was installed. These doorbells cause a great deal of annoyance and interference to staff not only due

to the volume, which has been measured at levels as high as 80.6 dB LAmax in one case, but with

visitors constantly pushing the buzzer until the entrance door is opened. Staff felt that visitors did not

appreciate that they may be busy on the ward and could not simply ‘drop everything’ to answer the

bell.

In the post study meeting with staff at GOSH it was felt that limiting the number of times the doorbell

rang to once every 30 seconds would help a great deal in alleviating this annoyance. Staff also felt

that somehow setting ward visitors’ expectations regarding the length of time it may take to answer

the door might also help, perhaps using something as simple as a clear written notice on the entrance

door.

12.3.5. Rubbish bins

Rubbish bins on several of the study wards were found to cause annoyance and disturbance to

patients, and high levels of noise. Although many of the bins in use have been specifically designed to

have quiet closing lids, they are often positioned too close to a sink or wall. On opening, the lid hits

the nearby surface or object, causing a loud bang and entirely defeating the point of the quiet closing

mechanism. The body of the bin is also a problem, as it is generally solid and undamped; hence

discarding a heavy object also causes noise.

Design improvements have been made to rubbish bins, with the addition of quiet closing mechanisms,

however the correct siting of the rubbish bin is imperative; wall spacers and some additional damping

in the body of the bin would alleviate much of this unwanted noise.

12.3.6. Ward furniture

Furniture scraping on the floor was found to be a source of high level noise in several study wards.

This could be simply and cheaply controlled by fitting rubber feet or wheels to the chairs and other

furniture used.

12.3.7. Wheeled equipment

Much of the equipment used on the wards has wheels to allow for portability. This includes patient

beds, ward furniture, medical equipment, as well as the standard ‘trolleys’ used to deliver meals,

drinks, medication, linen and other supplies. Noise from trolleys has been measured at levels as high

as 85 dB LAmax, which is due to in part to inherent flaws in their design. Many of these pieces of

equipment are metal; have no damping; and have ill-adjusted wheels and unsuitable tyres.

It is interesting to note that the Ministry of Health Hospital Design Note 4: Noise Control (Her

Majesty’s Stationery Office, 1966) recognised trolleys as a major source of noise, recommending that


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good quality rubber tyres be fitted. It is very sad to think that 45 years later, these inherent design

flaws have not been improved.

12.3.8. Ring binders

In all the study wards, patient notes and other reading materials are stored in ring binders. Without

exception the clicking shut of these ring binders was captured at high levels and on numerous

occasions during the study, with measured levels as high as 85 to 90 dB LAmax. Often these levels

were captured at a nurse station during the night, when nursing staff were catching up on

administrative tasks. It is thought that other types of folder could easily be sourced which do not make

use of the ring binder spring loaded mechanism and therefore do not cause unnecessary disturbance

to those patients close by, who may be asleep or trying to sleep.

12.3.9. Doors

Banging doors were cited as disturbing in a number of the study wards and this could be simply

remedied by fitting or adjusting quiet door closers, or in the case of metal cupboards, installing some

damping.

One occasion of poor workmanship was discovered in relation to a heavy fire door. Although the quiet

closer was working correctly, the door frame was too large and on closing the door would rattle loudly,

the sound carrying down the main ward corridor.

Whether due to poor maintenance, lack of a quiet door closer or poor workmanship, all these

problems are relatively cheap to fix. However, what appears to be unclear is the reporting mechanism

for staff to log a fault of this nature. An example of this is illustrated in the pilot study ward at GOSH.

Staff here became so irritated with doors banging that they took matters into their own hands and

draped towels over the doors to prevent the noise. This was soon stopped by the ward manager on

infection control grounds. It is unknown if the problem was rectified.

12.4. Human behaviour

Human behaviour and attitudes are inherently difficult to change in the long term. Studies have shown

that short term noise level improvements can be gained if individuals are made aware of the impact of

their actions in relation to noise. However, this is difficult to implement successfully for any length of

time without a great deal of support from ward management to ensure all policies are strictly adhered

to.

There are many aspects of behaviour cited by both staff and patients in the subjective responses to

the noise environment. Noise level measurements also captured certain activities causing high levels

of noise. Cleaning and the changing of rubbish bins are very necessary activities, but ones that a

number of patients felt could be carried out more quietly. Noise level measurements also found this to

be the case. Loud staff telephone conversations were also mentioned, especially when they were of a


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personal nature and on a mobile phone. Domestic staff talking loudly or shouting at each other across

the ward was found to be annoying by the patients.

Visiting time was listed by a high percentage of staff as annoying and causing interference to their

work. Patients also found large numbers of visitors round a bed disturbing, and some felt that visiting

hours should be more strictly adhered to. Ward managers had very differing views regarding leniency

around visiting times, with some managers feeling that the more contact patients had with their friends

and family, the better. This is obviously a very subjective area, but it is important that visitors are

respectful of other patients on the ward and should also be aware of staff and the duties that they

must perform. If visitors are being loud and impolite it is surely up to the senior members of staff to

control the situation and let it be known that their behaviour is unacceptable and will not be tolerated.

Noise levels in single rooms were often found to be higher and less consistent than those measured

in multi-bed bays. In some instances this was due to the behaviour of those visiting the patients. High

noise levels due to conversation were often captured for long periods of time, with visitors staying on

for an hour or more after the end of designated visiting hours. On occasions staff appeared to turn a

blind eye as the doors to the rooms could be closed and so this would not cause a disturbance to the

other patients on the ward. Of course all patients are recovering and need their rest, and so could

these longer, louder visiting times be potentially detrimental to the patient’s recovery?

Patients crying out in confusion or pain were found to be annoying and disturbing by other patients,

particularly on the medical wards, where there are a higher percentage of elderly patients being cared

for. Patients suffering from confusion or dementia can often be very vocal and it can be both

distressing and disturbing to the other patients in the bay. This is a particularly difficult area to control,

short of segregating these patients, which is not practical in a medical ward running at nearly 100%

occupancy at all times.

Every patient on the study wards was provided with entertainment in the form of a telephone, TV and

radio console, often provided by ‘Patientline’. In most cases patients were provided with headphones

to watch TV or listen to the radio without causing disturbance to others. However, ward managers

admitted that the use of these headphones was not always enforced, resulting in many patients listing

TV / radio use as annoying and disturbing. Perhaps if staff were more aware of the level of annoyance

/ disturbance this causes others, they would be more inclined to enforce headphone use.

Questionnaire responses indicated that on some of the study wards mobile phone use caused

annoyance and disturbance to patients. The use of mobile phones in hospital wards is a contentious

issue with each hospital having their own discretionary policy. The policy at Bedford Hospital, for

example, prohibits the use of mobile phones on the wards, suggesting calls are made in the lobby

areas directly outside the ward. Questionnaire responses from one of the study wards at this hospital

indicated that this policy was not being enforced. Ward managers themselves also have their own

opinions on the use of mobile phones. One of the study ward managers felt so passionately that the

telephone charges incurred as a result of the ‘Patientline’ system were unacceptable, that she allowed

patients to use their mobile phones on the ward.


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12.5. World Health Organisation guidelines

As discussed in Chapter 2, the most recent edition of the World Health Organisation (WHO)

Guidelines for Community Noise was published in 1999 (Berglund et al, 1999). In relation to noise in

hospitals, the guidelines state that ‘the critical effects of noise are on sleep disturbance, annoyance

and the communication interface, including interference with warning signals’. A summary of the

guidelines is shown in Table 12.1.

Table 12.1 – World Health Organisation guidelines for hospital wards and treatment rooms

Specific Environment Critical Health Effects

LAeq (dB) Time Base (Hours) LAmax (dB)

Hospital, ward rooms, indoors

Sleep disturbance 30 Night time (8 hours) 40

Hospital, ward rooms, indoors

Sleep disturbance 30 Day time and evenings (16 hours)

-

Hospital, treatment rooms, indoors

Interference with rest and recovery

As low as possible

The LAeq value stipulated by the guidelines for both day and night time on a ward is 30 dB LAeq.

Interestingly, no noise levels measured in the study wards were found to comply with these levels,

which is in accordance with the findings by Busch-Vishinac et al in 2005. In their comprehensive study

the authors compiled data from all comparable studies post 1960 which listed LAeq noise

measurement values. Not one single study showed a hospital which complied with the WHO

guidelines for hospital noise. This raises the question of the validity of these guidelines.

The WHO guidelines also stipulate a time base in terms of day and night, with day time beginning at

07.00 and ending at 23.00. Noise levels collected in each study ward suggest that this division is not

realistic for hospital wards, with ward activity generally beginning earlier than 07.00 and decreasing

before 23.00. It was also noted that noise levels were generally found to diminish after the evening

meal had been served at around 18.30, suggesting that an ‘evening’ period may also be applicable

and more realistically reflect activity levels on the wards.

In Chapter 6, the fact that the noise levels decreased earlier during the evening was assumed to be

because this was a children’s ward. However, further analysis of adult wards suggests that this is the

case for all wards.

12.6. Acoustic parameters

As discussed in Section 11.2.3, noise measurements have been presented throughout this study as

average day and night LAeq levels for each bay, with average hourly noise levels (LAeq,1hr) plotted over

24 hour intervals. Levels presented in these ways do provide a general indication of the daily patterns

of noise and the overall levels measured in each bay, but are generally found to be very similar with


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relatively small amounts of variation. Busch-Vishniac et al (2005) also encountered this lack of

variation, which was surprising given that their data was gathered from widely differing sources.

To illustrate the fluctuating nature of the measured noise, and help build up a more detailed picture of

its content, high level noise events (over 70 dB LAmax) have been investigated throughout this study

and these are reported in some detail in Chapters 7 and 9. The use of the trigger files captured has

provided a means of identification of all high level sources of noise, and it is felt that by looking at the

types and also the numbers of high level noise sources over a measurement interval, this study has

gone some way in providing data to describe the realities of the noise climate on the wards.

12.7. Conclusions

The discussion in this chapter has shown that it is important to consider noise control at the design

stage of a hospital building. However, much of the impact of noise is related to the patient group, the

activity and behaviour of staff and patients, and the supporting equipment.

The next chapter presents the overall conclusions to the study and recommendations for further work.

Acoustic Design for Inpatient Facilities in Hospitals Conclusions

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13. Conclusions

13.1. Introduction

This study has investigated, through objective and subjective surveys, the noise climate and acoustic

design within general inpatient facilities in the UK, and their influence on the acoustic comfort of

patients and staff. Noise and acoustic surveys have been carried out in six inpatient wards in three

major UK hospitals, with corresponding questionnaire surveys of staff and patients.

It has been shown that high levels of noise are not confined to ICU and operating theatres, but are

found to be significant throughout inpatient wards in UK hospitals.

Overall conclusions from the study are presented below, together with recommendations arising from

the study and suggestions for further work.

13.2. Overall conclusions


The study has highlighted the need to understand the way the building will be used when occupied

when specifying the acoustic design of a hospital building. Without due consideration expense may be

incurred in relation to the installation of acoustic doors and sound attenuating material, when in reality

they may be of no actual benefit. This has been illustrated by the ‘open door nursing’ policy in use in

UK hospitals, where staff are trained to nurse with doors open at all times for observational purposes.

Careful thought must be also given to the ward layout to ensure that there are no direct sound paths

from potentially noisy areas, such as kitchens, healthcare utilities and nurse stations, to patient

accommodation.

It has been shown that lower reverberation times result in lower noise levels. This stresses the need

for sufficient acoustic absorbency on the wards in order to reduce noise, which can be attained by

using good quality acoustic ceiling tiles. A new range of ceiling tiles that withstand stronger cleaning

agents are now generally available for use in hospitals following infection control concerns. This

proactive response by the manufacturers has ensured that in future the acoustic design of the wards

need not be compromised by Control of Infection policies.

The study found some evidence to suggest that there was a slight downward trend in noise levels and

building age. Measured day time noise levels were found to decrease between buildings built in the

1970’s, 1980’s and in the last ten years suggesting the more recent use of acoustic design guidelines

may be having some effect.


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13.2.2. Patient accommodation

The study has found that contrary to general assumption, noise levels are unrelated to bay size and

numbers of beds, with some of the highest noise levels measured in single bed rooms. Furthermore,

patients in single rooms were found to be more annoyed by day time noise and more disturbed by

night time noise than those in multi-bed bays.

Conversational privacy was rated most poorly by patients in 3-bed bays, with improvements found in

four to twelve bed bays. 100% of patients in single rooms were found to be satisfied with speech

privacy.

Measured noise levels in a medical and surgical ward at the same hospital were found to be similar,

but the sources of the noise and the staff and patient perceptions differed.

13.2.3. Staff and patient perceptions

Ratings of noise annoyance and interference by staff at the main study hospitals were generally low;

mostly in the ‘slightly’ to ‘moderately’ range. However, there were noticeable differences found with

longer term staff (> 5 years service) rating noise interference more highly than noise annoyance, and

more highly than staff who had worked on the ward or in the hospital for a shorter time.

Analysis of the patient questionnaire responses from the main study sites indicated a shift in the

attitude amongst longer term patients (> 3 weeks stay) to the noise climate, with increased sensitivity

during the day but decreased sensitivity at night. This may suggest a certain amount of

acclimatisation to night time noise. It was also found that patients in the 41-50 age group were more

highly annoyed and disturbed by noise than any other age group.

13.2.4. Ward equipment

The study shows that the cacophony of alarms and tones emitted by the electronic equipment in use

on the ward are a major source of noise, with the nurse call, internal telephone, ward doorbell and

medical equipment continually cited as causes of annoyance throughout the study. Ward staff found

much of this equipment to be either inflexible, faulty, over complicated or not fit for purpose. Training

in the use of electronic equipment appeared to be lacking.

Much of the noise attributed to ward furniture could be rectified by simple noise control measures,

such as fitting rubber feet or wheels to furniture; fitting and maintaining quiet door closers; a common

sense approach to the positioning of rubbish bins; and the replacement of ring binders.

Simple ward maintenance was found to be an issue, with no clear fault logging process available to

sort out problems such as an ineffectual door closer.


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13.2.5. Human behaviour

Although human behaviour and attitudes are inherently difficult to change in the long term, it is felt

that if staff, patients and visitors were made aware of the effects of their actions on the noise climate,

they might think more carefully in the future. Thus, education of users of a hospital, accompanied by

support and further enforcement by senior management may be needed to change the current culture

to a culture of ‘quiet’.

13.2.6. Guidelines

Most of the current acoustic design guidelines were not found to be applicable to an occupied

building; only the WHO guidelines for healthcare were concerned with noise levels in an occupied

ward. However, these guidelines have been shown to be unrealistic and a review is needed of both

noise levels and day and night divisions.

13.3. Recommendations

The study has highlighted the need for adequate consultation with the building’s users before the

acoustic design criteria is specified for a new or existing building. This will allow a realistic set of

acoustic requirements to be established that will positively support the building’s users and ensure

that money is not spent on un-necessary acoustic treatment.

Post occupancy surveys should be carried out some months after a new hospital building is first

commissioned to ensure that the building is functioning as it was designed. Staff should be involved in

this process, providing feedback regarding any problems they may have in terms of their environment

and the ward systems. Feedback mechanisms should be put in place that encourage problems to be

reported, no matter how small.

Due to a lack of funding for new hospital buildings, refurbishment of the existing hospital building

stock will be carried out over the next decade more extensively than ever. To ensure that the limited

funding available targets the correct areas, it is important that adequate consideration is given to the

staff and patient experience. Some of the differences in opinion identified during the study highlight

the need to focus on areas of the greatest impact. For example, fitting expensive double glazed

windows to an entire building may not have as much effect as changing the suspended ceilings, or

making changes to some of the more problematic ward systems.

Ongoing ward maintenance needs a proper reporting structure to be put in place. If this does not

exist, busy staff will simply ‘put up with’ issues that cause them annoyance and interference,

assuming that nothing will be done. Regular reviews either by the estates teams or by ward

management, who subsequent report to the estates teams, should be carried out.


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Adequate training on the use of ward systems should be provided for new and existing staff and this

should be an ongoing process.

It is imperative that manufacturers take the noise impact into consideration when developing any type

of new system or piece of equipment to be used on a hospital ward. Collaboration with staff is strongly

recommended to ensure that their requirements are incorporated. Simplicity of use should also be a

priority.

It is felt that with properly implemented and maintained systems and equipment; an effective feedback

system; a proactive approach to the management of noise issues by senior staff; and a common

sense approach to noise control, many of the issues highlighted by the study could be improved and

even eradicated completely.

13.4. Further work

The following areas would benefit from further work:

� Raising the awareness of hospital ward equipment and systems manufacturers as to the

potential impact of their equipment on hospital noise, and on staff and patients.

� Design of medical equipment alarms to ensure that tones are only emitted when necessary,

and that the alarms themselves are suitable for the event type.

� Development of more realistic guidelines for noise levels in occupied wards, including a more

suitable day, evening and night division.

� Investigation of the feasibility and the trialling of replacement technology which incorporates

wireless and silent technology that could replace existing systems such as the internal

telephone, doorbell and nurse call.

Acoustic Design for Inpatient Facilities in Hospitals References

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Acoustic Design for Inpatient Facilities in Hospitals Appendices

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Appendix A

1. Study publicity poster

2. Staff information sheet

3. Staff questionnaire

4. Patient questionnaire

5. Response from the National Research Ethics Service (NRES)

6. Ethical approval received from London South Bank University


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257

Is it too Is it too Is it too Is it too

noisy?noisy?noisy?noisy?

Research is currently being carried out by the Estates Team here at XXXX

Hospital together with London South Bank University. The purpose of this

research is to understand the impact of noise on patients and staff in the wards.

We are also keen to find out whether the design and materials used in our

buildings help to make the buildings less or more noisy for everyone who uses

them.

Research into the Acoustic Environment

The first part of the research will involve taking some

sound level measurements. This will help us to build

up an understanding about the noise levels and

sources of high level noise in the ward environments.

To enable these measurements to be made, a portable

sound level meter will be used. This meter measures

sound levels in Decibels. The meter is small and

unobtrusive and please be assured that it will be

sterilised prior to use.

The second part of the research is about understanding your feelings about

noise - the patients and staff who spend time in the ward environments. A short

questionnaire of no more than 10 minutes in length will allow us to build up an

understanding of how the building is viewed in terms of noise. This will be on a

completely voluntary basis and all information collected will be anonymous.

Your involvement will be greatly appreciated to help positively influence the

environment for the future.

Sound Level Meter

Research Steps

For further information or to register your interest in participating in the study

please contact XXXX in the Estates Team. Alternatively email Nicky Shiers at

[email protected]

1.


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258


You are being invited to take part in a research study. Before you decide it is

important for you to understand why the research is being carried out and what it will

involve. Please take time to read the following information carefully. Talk to others

about the study if you wish.

Please ask us if there is anything that is not clear or if you would like more

information. Take time to decide whether or not you wish to take part.

The aim of this research is to investigate the impact of noise on the staff such as

yourself, in the clinical environment in which you work. The results will enable us to

understand whether the design and the materials used in the hospital buildings have

a positive or negative impact on your acoustic comfort.

This study is being completed as part of a PhD at London South Bank University and

is being run in conjunction with the Estates Team here at XXXX Hospital.

The initial part of the study will involve the researcher making some sound level

measurements. This will help to build up an appreciation of the actual noise levels

and sources of high level noise in the ward environments.

The second part of the research will involve the completion of a questionnaire to

explore your perceptions of the ward environment in relation to noise. The

questionnaire should take between 5 and 10 minutes to complete.

Of course, it is up to you to decide whether or not to take part. If you do so, you will

be given this information sheet to keep. You are still free to withdraw at any time and

without giving a reason.

No personal information will be asked of you in the questionnaire and all information

you do provide will be handled in a confidential manner and stored in a locked filing

cabinet and on a password protected computer in an environment locked when not

occupied. Only the researcher and supervisor will have direct access to the

information. Any reference to you will be coded. This information will be held until the

end 2012.

If you have a concern about any aspect of this study, you should ask to speak with

the researcher who will do their best to answer your questions. The contact details of

the researcher are shown at the end of this sheet. If you would like any further

Is it too Is it too Is it too Is it too

noisy?noisy?noisy?noisy?

2.


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259

information regarding this study or have any complaints about the way you have

been dealt with during the study or other concerns you can contact: Rosemary

Glanville, Head of the Medical Architecture Research Unit on 0207 815 8329, who is

the Academic Supervisor for this study. Finally, if you remain unhappy and wish to

complain formally, you can do this through the University’s Complaints Procedure.

Details can be obtained from the university website: http://www.lsbu.ac.uk/research

Researcher’s Contact Details:

Mrs Nicola Shiers

Medical Architecture Research Unit

Faculty of Engineering, Science and the Built Environment

London South Bank University

103 Borough Road

London

SE1 0AA

T: 0207 815 8395 E: [email protected]


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260


This questionnaire forms part of a study being carried out by the Estates and

Facilities Team here at XXXX Hospital together with London South Bank

University. The purpose of research is to understand the impact of noise on staff

and patients in the wards.

The questionnaire should take between 5 and 10 minutes to complete and is of

course completely voluntary. By completing this questionnaire you are

consenting to take part in this study. The responses which you give will be

completely anonymous.

The questions concern how annoyed you are by noise and how much noise

interferes with your ability to do your work.

About You

1. Are you?

� Male � Female

2. What age are you?

� Less than 20 � 20-30 years � 31-40 years

� 41-50 years � 51-60 years � 60+ years

3. What staff grade are you? ………………

4. How long have you worked on this ward?

� Less than 1 year � 1-2 years � 2-3 years


5. How long have you worked at this hospital?

� Less than 1 year � 1-2 years � 2-3 years


3. SSSSoundoundoundound IN IN IN IN

YOURYOURYOURYOUR

HOSPITALHOSPITALHOSPITALHOSPITAL


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261

About Your Environment

1. Do you ever feel annoyed by noise while you are at work?

� Not at all � Slightly � Moderately � Very much � Extremely

Please indicate on a scale from 0 to 4 how much you are annoyed by each of

the following noises (0 indicating ‘not at all’ and 4 indicating ‘a great deal’)

0 1 2 3 4

External noise (traffic, aircraft etc) � � � � �

Doors banging � � � � �

Internal telephones ringing � � � � �

Staff talking on the telephone � � � � �

Nurse call � � � � �

Door bell � � � � �

Footsteps � � � � �

Medical equipment alarms � � � � �

People talking � � � � �

Cleaning � � � � �

Rubbish Bins � � � � �

Trolleys � � � � �

Meal times � � � � �

Television / radio � � � � �

Mobile phones ringing � � � � �

People talking on mobile phones � � � � �

Visiting time � � � � �

Other (please specify and rate)

…………………………………………………….. � � � � �

…………………………………………………….. � � � � �

…………………………………………………….. � � � � �

…………………………………………………….. � � � � �


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262

2. Overall, how much do you feel that noise interferes with your ability to do

your work?

� Not at all � Slightly � Moderately � Very much � Extremely

Please indicate on a scale from 0 to 4 how much each of the following noises

interferes with your ability to do your work (0 indicating ‘not at all’ and 4

indicating ‘a great deal’).

0 1 2 3 4









General conversation � � � � �










…………………………………………………….. � � � � �

…………………………………………………….. � � � � �

…………………………………………………….. � � � � �

…………………………………………………….. � � � � �


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263

3. It is important for you to be able to hear some sounds in order for you to

carry out your job effectively.

Please rate the importance of each of the following sounds on a scale from 0

to 4, where 0 indicates ‘not at all important’ and 4 ‘extremely important’.

0 1 2 3 4


Conversations with colleagues � � � � �

Conversations with patients � � � � �

Equipment alarms � � � � �

Patients calling out � � � � �

Patient activity � � � � �


…………………………………………………….. � � � � �

…………………………………………………….. � � � � �

4. Sometimes high levels of background noise can make it difficult to hear

important sounds. Please indicate on a scale from 0 to 4 how difficult it is to

hear in the following locations:

I can It is very

always difficult

hear to hear

0 1 2 3 4

Nursing Station � � � � �

Hallway � � � � �

4 bed bay � � � � �

Single patient room � � � � �

Treatment Room � � � � �

If you have any further comments regarding noise, please write them

in the space below.

………………………………………………………………………………………………………………………………

………………………………………………………………………………………………………………………………

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

………………………………………………………………………………………………………………………………

THANK YOU FOR TAKING THE TIME TO

COMPLETE THE QUESTIONNAIRE


___________________________________________________________________________________________________________________

264


This questionnaire forms part of a study being carried out by the Estates and Facilities

Team here at XXXX Hospital together with London South Bank University. The purpose of

research is to understand the impact of noise on patients and staff in the wards. We are

also keen to find out whether the design and materials used in our buildings help to

make the buildings less or more noisy for everyone who uses them.

The questionnaire should take between 5 and 10 minutes to complete and is of course

completely voluntary. By completing this questionnaire you are consenting to take part

in this study. The responses which you give will be completely anonymous.

About you

1. Are you?

� Male

� Female

2. What age are you?

� Less than 20

� 20-30 years

� 31-40 years

� 41-50 years

� 51-60 years � 60+ years

3. How many days have you been at hospital this time? (Please enter number in boxes

below)

� days Bed Number�

SSSSoundoundoundound IN IN IN IN

YOURYOURYOURYOUR

HOSPITALHOSPITALHOSPITALHOSPITAL

4.


___________________________________________________________________________________________________________________

265

About Your Environment

1. During the daytime in this ward, would you say it is:

� Very quiet � Quiet � A little noisy � Very Noisy � Extremely Noisy

2. Are you ever annoyed by noise during the daytime?

� YES � NO

If you answered ‘YES’, please indicate on a scale from 0 to 4 how much you are

annoyed by each of the following noises (0 indicating ‘not at all’ and 4 indicating ‘a

great deal’)

0 1 2 3 4


















Other patients crying out � � � � �


…………………………………………………….. � � � � �

…………………………………………………….. � � � � �

…………………………………………………….. � � � � �

…………………………………………………….. � � � � �


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266

3. After lights are turned out and you are trying to sleep, would you say the ward is:

� Very quiet � Quiet � A little noisy � Very Noisy � Extremely Noisy � Don’t know

4. Are you ever disturbed by noise after lights out?

� YES � NO

If you answered ‘YES’, please indicate on a scale from 0 to 4 how much you are

disturbed by each of the following noises (0 indicating ‘not at all’ and 4 indicating ‘a

great deal’)

0 1 2 3 4










Rubbish bins � � � � �





Other patients crying out � � � � �


…………………………………………………….. � � � � �

…………………………………………………….. � � � � �

…………………………………………………….. � � � � �

…………………………………………………….. � � � � �


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267

5. Are there any noises that you actually finding comforting?

Please specify ………………………………………………………………..

……………………………………………..................

6. When doctors and nurses talk to you, can you always hear them clearly?

� I can always clearly hear what people say

� Occasionally high levels of noise make it hard to hear

� Often high levels of noise make it hard to hear

7. Do you consider that it is possible to hold a private conversation here?

� YES � NO

8. If you answered ‘yes’ to question 7 and wanted to hold a private conversation, would

you:

� Use your normal voice

� Lower your voice

� Take some other precautionary measure

If so please specify ……………………………………………………

9. Do you ever feel that there is too little sound in here?

� YES � NO

10. Do you suffer from any hearing impairment that you know of?

� YES � NO

If you have any further comments regarding noise, please write them in the space

below.

………………………………………………………………………………………………………………………………

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

………………………………………………………………………………………………………………………………

THANK YOU FOR TAKING THE TIME TO

COMPLETE THE QUESTIONNAIRE


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268

5. Copy of email response from the National Research

Ethics Service for the NHS (NRES)

RE: Research Enquiry

NRES Queries Line [[email protected]]

To: Shiers, Nicola

Cc:

Your query was reviewed by our Queries Line Advisers.

We would classify this as a type of service evaluation and it does not

require REC review.

Regards

Queries Line

National Research Ethics Service

National Patient Safety Agency

4-8 Maple Street

London

W1T 5HD

Website: www.nres.npsa.nhs.uk

Email: [email protected]

Ref: 04 /31


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269

6. Ethical approval received from London South Bank

University (scan of relevant signatures)


___________________________________________________________________________________________________________________

270

14. Appendix B

1. Great Ormond Street Hospital parent / patient questionnaire comments

2. Bedford Hospital staff questionnaire comments

3. Bedford Hospital patient questionnaire comments

4. Addenbrooke’s Hospital staff questionnaire comments

5. Addenbrooke’s Hospital patient questionnaire comments

6. Comforting sounds


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271

1. Great Ormond Street Hospital parent / patient questionnaire comments

Comments made are listed below:

� ‘General level is ok but sometimes conflicting TV/radio can be annoying. Would free

earphones be appropriate?’

� ‘Noise of a working area is never a problem. Sometimes silence is nice. Children

communicating and other carers is very enjoyable and helpful.’

� ‘Headphones for children after lights out?’

� ‘Some TV’s can be very loud.’

� ‘Would be helpful if the entrance door to the ward could be closed at night time. This would

eliminate a lot of the noise from the corridor and the other wards.’

� ‘Some noise depends on where your child’s bed is situated, so because we were away

from the nurse’s station the phone and conversation did not affect us, but the doorbell was

quite noisy.

� ‘Patients have TV’s very loud and have them on during the night. Each patient should be

issued with ear phones so that TV/radio noise does not disturb others in the wards.’

� ‘The drilling has been a mild nuisance and the fire alarm going off for 35 minutes at

5.20am made sleep impossible. The utility room opposite our room is used frequently

during the day and night and the door makes a loud bang every time which kept us both

awake. Quiet closers on the doors would help.’

� ‘It is quite difficult to determine what is too noisy as it is so dependent on what situation

your child is in at the time.’

� ‘We have spent the last three days with our daughter recovering from spinal surgery. We

are in a 4-bed bay with two other patients and next to a child who has special needs and

benefits from loud music. She is also very vocal and both we and our daughter found this

intrusive when she was feeling very unwell. This was not the fault of the other family, but

was not conducive to our well being.

Suggestions:

� Provide wireless headphone (perhaps two sets per bed to allow a visitor

to listen as well as the patient).

� Limit the volume on each TV.

� Put speakers closer to the patient – when 3 ceiling mounted TV’s are set

to different channels it is a real cacophony of sound.

To illustrate how difficult it was at times, our daughter was lying with her fingers in her

ears’.


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272

2. Bedford Hospital staff questionnaire comments

� ‘I wish the curtains between patient’s beds could be sound proofed so you could have a

confidential / private conversation without the rest of the bay hearing’.

� ‘I am partially deaf so find it difficult to hear when there is a lot of background noise. I often

have to ask other staff members to repeat themselves or to clarify what they have said’.

� ‘I don’t think there is too much of a problem on the ward regarding noise’.

� ‘Did you know? There are crickets living in the elevators at Bedford hospital, chirping at

night’.

3. Bedford Hospital patient questionnaire comments

Medical ward patients:

� ‘It appears that if a patient is noisy and aggressive their attentions are responded to

quicker, that is bed pan, bathing etc. Quiet patients are often ignored or completely

forgotten as the staff are over pushed and failing in essential human contact in most of

their functions. Perhaps quiet areas could be assigned and less aggressive patients

attended to quicker and more efficiently rather than excluded by aggressive nutters who

dominate the ward by vocal, noisy and constant requests for un-needed “help” ’.

� ‘We only had one night of noise’ – it should be noted that this was over the course of an 8

day hospital stay.

� ‘Kitchen door left open after meal times so loud banging / washing up can be heard.

Cleaning staff shouting at each other from one end of the room to kitchen.’

� ‘Staff making personal calls on mobiles. I don’t really want to know whom they met in the

pub last night and whether they will go out for a curry or Chinese.’

� ‘I’m very grateful for the kindness of all the staff – from kitchen staff to doctors.’

� ‘Only sometimes noisy when a large family get around the bed, for example 6 or 7 people.’

� ‘Angry patients mouthing at everyone and not taking full responsibility for their own

misgivings.’

� ‘I accept that there is bound to be a certain level of noise day or night, and understand the

difficulties that staff have to do their job and at the same time try not to disturb the

patients.’


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273

Surgical ward patients

� ‘When the background noise is low as at night, individual noises are more disturbing’

� ‘The bay is very close to the entrance door and the reception desk. There is continual

traffic past bay 1 to the other bays. Perhaps the desk should be located before the

entrance door.

� ‘I think staff can be very inconsiderate during the night – laughing out loud – slamming

doors – to us who are not necessarily ‘worn out’ they sound like clanging cymbals. It is not

easy to sleep when it is very light.’

� ‘As a poor normal light sleeper I find the lights left on during the night really hard. Have to

use alarm to get light switched off.’

� ‘The ward is the quietest ward I have been on.’

� ‘Wherever you are these days you expect to hear a certain amount of noise such as traffic,

and you take it for granted. One wouldn’t want to live in a totally silent world, missing bird

song and human voices.’

� ‘Thank you.’

� ‘The buzzer [nurse call] in the nurse station is a little disturbing.’ (This patient was in the 4-

bed bay directly opposite)’.

� ‘Visiting – very unclear times: are they the same at weekends?’ & ‘external noise very bad’

� ‘I found the noise at night more of a problem than my previous visit – my bed is the closest

to the nurse station so I get all the buzzer noises [nurse call] / phone calls etc and lots of

walking up and down. Some shoes squeak more than others!’

� ‘May I suggest that trolleys are fitted with pneumatic tyres – would cut out a lot of clatter. I

know cleaning has to be done and appreciate the cleanliness, but could it be done a little

quieter? Please thank the staff for all their help, assistance and very friendly attitude.’

� ‘Doors are ill-fitting and a constant annoyance.’

� Other sources of noise annoyance mentioned cited by one patient who was in a single

room – ‘outside building noises; water pipes / pumping sounds; truck outside moving

bins/rubbish – siren sounds when reversing; continual humming from electrical machine

outside; police/ambulance sirens throughout the day; obviously staff not shown how to


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274

move rubbish bins / bags quietly. The doors are the main problem banging, and staff agree

too.’

� ‘I accepted noise as part and parcel of ward life’.

� Patient staying in a single room and listed squeaky hinges on doors as annoying.

� Patient is disturbed by mobile phones ringing during the night and suggests that they

should be put on silent.

4. Addenbrooke’s Hospital staff questionnaire comments

� ‘Often construction noise can be heard on the ward. Obviously inevitable with planned

expansion, but this disrupts patient’s rest and peace and quiet’ (D8)

� ‘What may make noise felt more is the space (lack of) and narrowness of the ward’ (D8)

� ‘When visiting hours were restricted and all visitors came at a certain time it became quite

noisy within bays’ (D8)

� ‘The most annoying noise I can think of is relatives / others pushing the doorbell; then if

you don’t answer straight away they ring again and again. It is a noise that is too loud and

unnecessary’ (M4)

� ‘Noise and excessive noise is everywhere in the ward environment – none more irritating

than the specific sounds use to catch attention, especially those of the telephone – which

not only catches attention but causes some discomfort and stress when other tasks take

over. If these sounds were different – soothing but alertive and not repetitive, this may help

reduce stress’ (M4)

� ‘There is no emergency alarm sound in the staff room, so if you’re in there you can’t hear

an emergency call’ (N3)

5. Addenbrooke’s Hospital patient questionnaire comments

� ‘I’m glad research into this is being done as I greatly believe in the visual and acoustic

environment has great impact on one’s recovery.’ (D8)

� ‘Noises at night often make it hard to sleep.’ (D8)

� ‘Women in high heels walking in the corridors.’(D8)

� ‘I probably make most of it, so I apologise to other patients and the staff. Also I am not that

bothered about other patients crying out now, you get used to it.’ (D8)


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275

� ‘A set of earplugs should be issued to each person.’ (D8)

� ‘One prevalent cause of noise is dictated by fashion and could not easily be changed.

Today’s version of clear, open, optimistic and especially young person in hospital

employment is uninhibited and class-free. This is fine in many ways, but does leave a

range of opportunities for serious and comforting discourse socially unrepresented and

indeed of quite unfamiliar character.’ (D8)

� ‘Pleased with treatment from staff. Concerned – as a younger person should there be a

separate bay for the dementia patients – as fairly distressing at times when crying out.’

(D8)

� ‘The thumping of the external building work could not only be heard, but also felt coming

up through the floor and made conversations with visitors very difficult.’ (D8)

� ‘When a patient is continually shouting and crying out in pain then I would suggest trying

to isolate them from other patients.’ (D8)

� ‘Noise levels at night are extremely high and have kept me awake for 2 nights.’ (N3)

� ‘I feel that all staff respect patient’s privacy and deal with any problems that arise.

Sometimes visiting hours can be a bit noisy but to be expected, unless doing it to annoy

others’. (N3)

� ‘Patients talking on mobile phones and land lines late at night. Patients watching TV via

their laptops. Staff unwilling and unable to ask patients to stop using their mobiles and be

quiet. Foul language while using phones and in general conversation between visitors and

patients. Sleep is very important for recovery and there should be a set time for lights out

etc. Visiting times should be enforced!’ (N3)

� ‘I have a hearing problem that hearing aids can sometimes make surrounding noise very

disturbing, therefore I am not good at judging noise levels generally.’ (N3)

� ‘Some of the staff wearing heels and the noise of the doorbell. No one answering the

phone so it is always going off.’ (M4)

� ‘The turning on of TV’s / radios when on speaker is very annoying and inconsiderate,

especially first thing in the morning.’ (M4)

� ‘You have to give and take…. (M4)

� Maybe a hospital volunteer or WI member could be on call to answer the phone.

� When people are sick you are going to get noise.


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276

� Foreign accents are especially difficult for the elderly.

6. Comforting sounds

Bedford Hospital

� Traffic

� Life going on outside

� Nurse activity

� Nurses talking quietly

� Knowing someone is near

� Knowing staff are there

� Tea trolley (2 responses)

� Music on the radio (3 responses)

� Nurses' voices

� People's voices

� Silence

� Specific person's ring tone


� Knowing staff are there (4 responses)

� Floor cleaner (sent patient to sleep)

� Birds outside

� Listening to music /radio (3 responses)

� Noise of trains on nearby railway (2 responses)

� Singing, laughter, good humour

� Nurses comforting patients (2 responses)

� Tea trolley and nurse’s pleasant good mornings (2 responses)

� Voices of wife and daughters

� Droning noises – nebulizers, Hoovers etc

� Aircraft


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277

Appendix C

Corner corrections

Throughout the study, care was taken in the positioning of the microphone and associated equipment

was so as to minimise its impact on staff duties and patient care. There were also constraints

regarding of the length of cable between the microphone and the environmental case housing the

sound level meter (5m). In most instances these constraints meant that the microphone was situated

close to the edge of room, often in the corner, with the microphone suspended from the ceiling on a

300mm bracket.

Due consideration was given to the possible increase in sound pressure that may occur as a result of

wall or corner reflections. A number of tests were carried out to investigate this, with simultaneous

LAeq measurements made both in the centre of the room and at the main equipment location, that is

close to the corner or wall of the room. The results are shown in the table below. It can be seen that

the average difference between the measured levels was low (0.61 dB), and thus it was felt that no

correction to measured levels was required.

Position Date Start time Elapsed Time (m:ss) End Time LAeq (dB) Difference

Nurse station, D8 - in front of nurse station 58.5

Nurse station, D8 - microphone suspended in corner 56.9

12-bed bay, D8 - centre of the ward 59.0

12- bed bay, D8 - microphone suspended close to wall 59.1


4-bed bay, D8 - microphone suspended in corner of ward 63.1

6-bed bay, surgical ward, Bedford - centre of ward 48.0

6-bed bay, surgical ward, Bedford - microphone suspended in corner 46.6

Nurse station, surgical ward, Bedford - in front of nurse station 56.8

Nurse station, surgical ward, Bedford - microphone suspended above nurse station 56.7

4-bed bay 1, surgical ward, Bedford - centre of the ward 47.8

4-bed bay 1, surgical ward, Bedford - microphone suspended in corner 46.0


7-bed bay, D8 - microphone suspended in front of wall 61.4

Single room 3, surgical ward, Bedford - microphone in centre of room by bed end 50.3

Single room, surgical ward, Bedford - microphone suspended over the window 50.5

Single room 1, surgical ward, Bedford - microphone in centre of room by bed end 53.5

Single room 1, surgical ward, Bedford - microphone on mini tripod on light over mirror 53.2

4-bed bay 2, surgical ward, Bedford - centre of the ward 44.0

4-bed bay 2, surgical ward, Bedford - microphone suspended in corner 44.2


3-bed bay, D8 - microphone suspended in centre of ward close to wall 59.7

Average difference = 0.61 dB

-0.2

13.13.053.0213.10.0324.06.10

21.07.10 11.51.55 3.02 11.54.57

21.07.10 15.36.04 1.18 15.37.22

14.07.10 11.34.10 3.02 11.37.12

01.07.10 15.23.39 3.01 15.26.40

07.07.10 12.28.12 3.01 12.31.13

24.06.10 13.38.10 5.24 13.43.34

01.07.10 11.06.22 3.01 11.09.23

23.06.10 17.00.46 2.59 17.03.45

1.0

02.06.10 12.34.56 3.04 12.38.00

9.6.10 10.12.56 3.07 10.15.03

1.8

0.6

-0.2

0.3

1.6

-0.1

0.4

1.4

0.1

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