Reducing the Risk of Noise-Induced Hearing Loss Through Best Practices Theresa Y. Schulz, PhD,...

Reducingthe Risk of Noise-Induced Hearing LossThrough Best Practices

Theresa Y. Schulz, PhD, LtCol, USAF (ret.)

Topics

Noise And Acoustics

Motivating Workers

Noise Reduction

Reducing Costs for Hearing Loss

Noise + Acoustics

Noise + Acoustics

Non-Occupational Occupational

Noise + Acoustics

Noise-induced hearing loss is the most common permanent and preventable occupational injury in the world.

World Health Organization

Noise + Acoustics

Worker’s Compensation

In many countries, excessive noise is the biggest compensable occupational hazard. Cost of NIHL to developed countries ranges from 0.2 to 2% of its GDP. NIHL is on the rise globally. (Source: WHO)

Noise + Acoustics

United States Statistics

Most common occupational injury in the United States. 22 million US workers are exposed to hazardous noise at work on a daily basis. Approx. 8 million Americans suffer from NIHL. (Source: NIOSH, 2009)

NOISE AND ACOUSTICS ~ Hierarchy of Controls

ADMINISTRATIVE CONTROLS

• Rotate Workers

• Extended Breaks

•2nd/3rd Shift

ENGINEERING CONTROLS

• Buy Quiet

• Vibration Pads

• Enclosures

• Barriers

• Isolation

PERSONAL PROTECTIVE EQUIPMENT

Noise + Acoustics - Hierarchy of Controls

OSHA Update: Feasibility• Oct 2010 – Intent to change

interpretation of “feasibility”• Must use engineering controls that are capable

of being done

• First extended comment period then withdrew that interpretation• Proposing public hearings and asking NIOSH

and professionals for input

Noise + Acoustics - OSHA Update

Noise Reduction Rating(NRR)

How much noise is reaching the ear of the worker ?

That is completely unknown …

Noise Level = 100 dB

Noise Reduction Rating = 30 dB

(55 – 104 dB)

Noise Reduction Rating



• A laboratory estimate of the amount of attenuation achievable by 98% of users when properly fit

• A population-based rating ― some users will get more attenuation, some will get less

The NRR is only a population estimate,

not a predictor of individual attenuation.

• 10 human subjects tested in

a simulated industrial room

• Tested with ears open /

occluded at nine frequencies

• Each subject tested 3x

• NRR calculated to be

population average

A test subject in the Howard Leight Acoustical Lab, San Diego, CA, accredited by the National Voluntary Laboratory Accreditation Program (NVLAP)

Noise Reduction Rating – Determining an NRR

NRR

Attenuation

Num

ber

of t

est

subj

ects

14 18

1

2

3

4

1920 22 24

23 2528 30 3226

27

5

Noise Reduction Rating – Determining an NRR

NRR

NIOSH

EarmuffsNRR – 25%

Formable EarplugsNRR – 50%

All Other EarplugsNRR – 70%

OSHA

NRR ÷ 2

(feasibility of engineering

controls)

CSA

Class

A up to 100

B up to 95

C up to 90


De-Rating Methods

Fit Test

From Kevin Michael, PhD and Cindy Bloyer “Hearing Protector Attenuation Measurement on the End-User”

Noise Reduction Rating –

Real-World Attenuation ≠ NRR

192 users of a flanged reusable earplug ~ 27 NRR

Retraining and refitting

resulted in an average

14 dB improvement for this group

Real user

attenuatio

n

<0 to 38 dB

30

20

10

0

-10

Att

enu

atio

n i

n d

B

40

50NRR = 27 Multiple-Use Earplug

1.FIT 2. WEAR TIME

A worker who selects an earplug with an NRR of 30

effectively reduced his 8-hour NRR to just …

but then removes that HPD for just …

30 dB

5 min 10 min 30 min15 min

26 dB 24 dB 22 dB 18 dB

In noise exposures, small intervals of no protection quickly void large intervals of adequate protection.


Biggest Factors in Achieving NRR



• The EPA recently made an announcement about a proposed change to the Noise Reduction Rating [NRR]

• This is the first change in hearing protector regulation in nearly 30 years


Current NRR Label Mock-up of New Label

80th %

Minimally-trained

20th %

Proficient Users


Three New LabelsLABEL DESCRIPTION

Conventional HPD

Perform lab test with subjects who fit the protector after brief training

Estimates the range of protection achieved by 20% and 80% of users

Active Noise Reduction [ANR]

• Uses a Microphone-in-Real-Ear [MIRE] method to estimate protection

• Measured with ANR turned OFF and ON to show the additional attenuation from the ANR

Level Dependent/ Impulse Noise Reduction

• Testing will occur over a range of impulse noise levels. Multiple tests to determine lower and upper ranges of impulse noise reduction

• Will include two ranges to identify attenuation for passive and active modes

• 20 human subjects tested in

a simulated industrial room

• Subject trained then fits their

own earplugs

• Tested with ears open /

occluded at 9 frequencies

• Each subject tested 2x

• NRR calculated to be

population average


Determining New NRR

New NRR (NRsa)

Attenuation

Num

ber

of t

est

subj

ects

11 14 18

1

2

3

4

1920 22 24

23 25 2730 33

5

20% achieved > 26 dB80% achieved > 20 dB

2826


How to Apply the New LabelTwo-number range displays the estimated protection achievable by minimally-trained users [80%] versus proficient users [20%].

A wider range indicates greater variability in the fit of that HPD. Smaller ranges indicate more consistency of fit. For example, earmuffs will usually have a tighter fitting range than earplugs, and may have a smaller NRR range.

80% 20%


What Can I Do Now?

• Evaluate Noise Spectra to determine if spectral balance corrections will be necessary

• Upgrade to One-on-one Training research studies confirm that one-on-one training is superior to group training

Although the new labeling regulation takes effect whenever the final rule is published by the EPA, there are a number of actions you can take now to prepare your Hearing Conservation Program for the change.

NRSG table B = L C - L A -1 2 6 13

x = 20% 36.7 34.4 33.5 31.9x = 80% 29.8 25.5 24.1 22.9

ProtectionPerformance

0

5

10

15

20

25

30

35

40

45

50

-2 0 2 4 6 8 10 12 14 16

Noise Spectral Balance, B = L C - L A (dB)

Es

tim

ate

d N

ois

e L

ev

el R

ed

uc

tio

n, d

B

possible for a few motivated proficientusers to achieve or exceedpossible for most individually trainedusers to achieve or exceed

NRSG


What Can I Do Now?• Evaluate Current HPD

Selection to determine whether they are appropriate for your noise environment. Use the Howard Leight Hearing Protector Selector for recommendations.

• Update Hearing Conservation Training Program on proper fit of hearing protectors. Hold a “Toolbox Training” and hold a refresher fit training session.

http://www.howardleight.com/selector




What Can I Do Now?Use VeriPRO® fit testing

• Train how to properly fit HPDs• Select appropriate HPDs• Document adequate protection

Use QuietDose™

• In-ear dosimetry measures and documents the noise dose employee is exposed to during their work shift

Reducing Costs of Hearing Loss


2000-2010 12.4

0.3

10.5

26

17.9

0.30.4

10.2

22

0.1 Dermititis

Radiation

Occ Disease-Injury

Loss of Hearing

Contagious Disease

Cancer

AIDS

Mental Stress

Cumulative Injury

Other

Source: Texas Department of Insurance

Workers Compensation Claims Data


2010 18.7

11.6

28.8

15.3

13.1

11.80.6

Dermititis

Occ Disease-Injury

Loss of Hearing

Contagious Disease

Mental Stress

Cumulative Injury

Other

Source: Texas Department of Insurance

Workers Compensation Claims Data

Fit Testing In-Ear Dosimetry



Earplug Fit TestingProvides an accurate, real-world picture of your employees’ hearing protector effectiveness.

ID if your employees are:

• Getting the right protection• Need additional training• Need different earplug

Field Verification – Fit-Testing

As a problem solver:• Derating Schemes• One-on-One

Training• HPD Selection• NRR Change

Real-Ear

Attenuation at Threshold

(R.E.A.T.)


Loudness Balance

(Real-Ear Attenuation Above

Threshold)


Microphone in Real-Ear

(M.I.R.E.)


In-Ear Dosimetry


Microphone in Real-Ear

(M.I.R.E.)

Audiometric, IntregaFit,* 1,2

MultiFit

FitCheck*HPDWellFit

QuickFit 1

EARfit*SafetyMeter*

VeriPRO*

REAT, 1One freq REAT, 1One freq MIRE Loudness Balance

Sound booth Quiet Room Anywhere Anywhere

PAR PAR Derived PAR PAR

Any earplug Any earplug Modified or custom earplugs

Any earplug

COHC2Training included

COHC Training provided Training included


* Commercially available

OSHA Alliance: Best Practice Bulletin www.hearingconservation.org

Additional Information www.hearforever.org


Variation from Published NRR

-30

-25

-20

-15

-10

-5

0

5

10

0 10 20 30 40 50 60 70 80 90 100

Workers

Dif

fere

nce

in

dB Published

NRR

Distribution of PARs

0

2

4

6

8

10

12


Wor

kers


Distribution of PARs

0

2

4

6

8

10

12


Wor

kers

Personal Factors Gender

Age

Years in Noise

Ear Canal Size

Familiarity

Model of Earplug

Program Factors # Group Trainings

# Personal Trainings


Difference on 2nd / 3rd Test

-30

-25

-20

-15

-10

-5

0

5

10

Subjects

Va

ria

tio

n f

rom

NR

R Published NRR

Trying a second earplug often improves attenuation

REDUCING COSTS / CLAIMSReducing Costs of Hearing Loss

“How well can users predict their attenuation after a short fit-testing

training session?"


Fitting Tips

Ability to Predict Noise Reduction

Accuracy of estimate

(75% were within one category of actual PAR)

0

10

20

30

40

50

60

70

80

90

100

Same Category One off Two off Three off Four off

28%

47%

14%


"I know how to better fit my

earplugs now."

"I was amazed with the results

after being shown the proper way to

use earplugs.

"Learned A LOT about best

earplugs for me"

"I found a more comfortable fit. It

was very beneficial."

"Very glad I did the fitting test.

Now I know the correct way to fit my ear plugs.”

"Recently had threshold shift" "Found better

earplugs"


"Feel like am protected now!"

"I had no idea I was not using my

earplugs correctly."


In-ear dosimetry measures/records worker’s actual noise dose, with and without protection

Provides real-time monitoring and alerts when worker approaches/exceeds safe limits

Only metric with direct potential to measure and prevent further progression of occupational hearing loss

Research > Alcoa Intalco Works

Mean Hearing Threshold (2k, 3k, 4kHz): 2000 – 2007 (N = 46)

Employees using continuous in-ear dosimetry starting in 2005Mean hearing threshold (2,3, and 4 kHz)

Employees using continuous ESP starting in 2005 2000 - 2007 (N=46)

0

5

10

15

20

25

30

35

40

45

50

2000 2001 2002 2003 2004 2005 2006 2007

Year of test

Mean

HTL

3,4,6

kHz

ESP Introduced trend line


Preventive Action after NIHLIn practice, an OSHA-recordable STS is not a preventive action ….

It is documentation of a hearing loss after the fact.

0 2 4 6 8 10 12 14 16

Months

How soon will an employee suffering NIHL be re-fit / re-trained ?

“Best case scenario” per Hearing Conservation Amendment

In-ear dosimetry “worst case” scenario …

1 Day • Audiometric test • Retest • Notification


Training + Motivation

Show, Don’t Tell• Provide copy of annual

audiogram to worker• Use personal examples to

demonstrate consequences of hearing loss

• Ask questions:• What is your favorite sound?• What sound would you miss

the most if you couldn’t hear?• What sounds connect you to

people and your environment?


Personalize Hearing Loss


Training Materials• www.hearforever.org• www.hearingconservation.org• http://adl.grc.nasa.gov • www.cdc.gov/niosh/topics/noise• www.dangerousdecibels.org

www.hearforever.org/TXA&M

Demonstrate Future Risk


Send Clear Message On + Off Job

HC Part of Everyday Life• Include recreational hearing

conservation in annual training

• Provide extra HPDs for home use

• Promote Hearing Conservation at company/family events


Remove Barriers to HPD Use

Make HPDs Available• Highlight “where to find

HPDs” in annual training• Make sure HPDs are well-

stocked and accessible• Include group of workers in

selection process for increased acceptance

• Offer wide variety to match comfort, job requirements

Make Hearing Conservation Part of Your

Everyday Life

Download today’s presentation at

www.hearforever.org/TXAM

Reducing the Risk of Noise-Induced Hearing Loss Through Best Practices Theresa Y. Schulz, PhD,...

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