Juneau Flightseeing Noise Informational Work Session November 6, 2000
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Transcript of Juneau Flightseeing Noise Informational Work Session November 6, 2000
Juneau Flightseein
g Noise
Informational
Work Session
November 6, 2000
How is Noise Measured?
Single Event Metrics Maximum Noise Level (Lmax) Sound Exposure Level (SEL) Spectral Content of the Noise
Cumulative Noise Metrics Hourly LEQ Noise Level Time Above Noise Level DNL Noise Level Modified DNL Noise Level (8 am to 9 pm)
Single Event Noise Metrics
LEQ Noise Level Bonnie Brae
Time Above Noise Level Douglas 2th
TA75
TA65
TA55
DNL Noise LevelDouglas 5th
Modified DNL
DNL
Frequency Character of the NoiseWhy is some noise more annoying?
31.5Hz
63Hz
125Hz
250Hz
500Hz
1kHz
2kHz
4kHz
8kHz
16kHz
S1
S12
S23
S34
S45
S56
S67
S78
S89
S100
S111
S122
0
10
20
30
40
50
60
70
80
90
How does Noise Effect People?
Hearing Loss Speech Interference Sleep Interference Classroom Learning Physiological Response Annoyance
Speech Interference
0 5 10 15 20 25 30 40
50
60
70
80
90
100
110
120
TA L K E R T O L IS T E N E R D IS TA N C E IN F E E T
L O W
BA
CK
GR
OU
ND
NO
ISE
(dB
A)
H IG H
C O M M U N IC AT IO N IM P O S S IB L E
M A X IM U M V O C A L E F F O RT
A R E A O F N E A R LY N O R M A L S P E E C H C O M M U N IC AT IO N
E L E VAT E D V O IC E L E V E L
C O M M U N IC AT IO N P O S S IB L E
S H O U T
C O M M U N IC AT IO N D IF F IC U LT
SO U R C E: E nv ironm en tal Im pact A na lysis H andbook John G . R au and D av id C . Wooten , 1980
Sleep Interference
How does Noise Effect People?
Hearing Loss Speech Interference Sleep Interference Classroom Learning Physiological Response Annoyance
Annoyance (FAA Research)
Annoyance (NPS Research)
Factors that Affect Individual Annoyance to Noise
Primary Acoustic Factors Sound Level Frequency Duration Secondary Acoustic Factors Spectral Complexity Fluctuations in Sound Level Fluctuations in Frequency Rise-time of the Noise Localization of Noise Source Non-acoustic Factors Physiology Adaptation and Past Experience Listener's Activity Affects Annoyance Predictability of When a Noise will Occur Is the Noise Necessary? Individual Differences and Personality
Factors that Affect Noise Source Levels
Engine technology Aircraft technology
Rotor or propeller design
Power Level Prop Pitch Speed
Factors that Affect Noise Propagation
Distance from Noise Source 6 dB per doubling of the distance
Meteorology Temperature and Humidity Cloud Cover Wind Speed & Direction
Ground Absorption Soft or hard surfaces Terrain and shielding
Home Construction
Temperature and Humidity
Source: “Noise and Vibration Control”, by Leo
AVI 2
Helicopter Noise? Loudness of Helicopters
65 to 80 dBA
Viabilities Meteorology
• Alters path and noise propagation Speed
• Higher speed shortens the duration Point of Flight Path
• Loudness about the same in all modes but duration may change Altitude
• Change in 5 dBA per doubling of the distance Terrain and Ground Surface
• Hard vs. Soft surfaces Number of Helicopters
• Duration increases
Helicopter EventsBrotherhood Park
Long Duration Helicopter EventsBonnie Brae
Character of NoiseCharacter of Noise
AS350 AVERAGE DEPARTURE SPECTRA
0
10
20
30
40
50
60
70
80
20Hz
25Hz
31.5Hz
40Hz
50Hz
63Hz
80Hz
100Hz
125Hz
160Hz
200Hz
250Hz
315Hz
400Hz
500Hz
630Hz
800Hz
1kHz
1.25kHz
1.6kHz
2kHz
2.5kHz
3.15kHz
4kHz
5kHz
6.3kHz
8kHz
10kHz
12.5kHz
16kHz
20kHz
Frequency (Hz)
Le
ve
l (d
B)
Float Plane Noise? Loudness of Float Planes
65 to 80 dBA
Viabilities Meteorology
• Less important than with helicopters Propeller Pitch
• Changes the noise characteristics Point of Flight Path
• Takeoff usually louder than approach• Flight path important
Altitude• Lower level flights
Type of Aircraft• New generation technology is quieter
Number of Float Planes• Increases the duration
Float Plane EventsDouglas 5th
Character of NoiseCharacter of Noise
OTTER AVERAGE DEPARTURE SPECTRA
0
10
20
30
40
50
60
70
80
20Hz
25Hz
31.5Hz
40Hz
50Hz
63Hz
80Hz
100Hz
125Hz
160Hz
200Hz
250Hz
315Hz
400Hz
500Hz
630Hz
800Hz
1kHz
1.25kHz
1.6kHz
2kHz
2.5kHz
3.15kHz
4kHz
5kHz
6.3kHz
8kHz
10kHz
12.5kHz
16kHz
20kHz
Frequency (Hz)
Le
ve
l (d
B)
Overall Noise Ambient metric shows background levels in low 40 dBA Single Event
Typical single event peak aircraft levels 65 to 80 dBA Highest levels of 85 dBA Typical durations of helicopter events ranged from 1 to 3 minutes
Time Above during Daytime hours Aircraft noise is above clearly audible levels 15% to 25% of the time During Peak aircraft can be above clearly audible over 90% of the time Aircraft noise is above typical speech interference levels 2 to 5% of the time Aircraft noise is above higher interruption levels about 1% of the time
DNL Aircraft DNL noise levels ranged from 50 to 57 Peak DNL days were 3 to 5 DNL higher Modified DNL (summer daytime hours) about 1 to 3 dB higher
Spectral Content Unique low frequency content of helicopter noise Pure tones from variable pitch prop aircraft
1994 vs. 2000 Noise
Changes between 1994 and 2000 Increased Operations Improved Flight Paths Quieter Technology
Unique Issues at Juneau
Meteorology Closed terrain with limited flight
paths Water area Limited Research on this type of
aircraft noise Relatively low level noise with long duration
exposure Lower frequency noise sources