Juneau Flightseeing Noise Informational Work Session November 6, 2000

1. Juneau Flightseeing NoiseInformational Work SessionNovember 6, 2000

2. 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)

3. Single Event Noise Metrics

4. Bonnie Brae LEQ Noise Level

5. Time Above Noise Level Douglas 2th TA75 TA65 TA55

6. Douglas 5th DNL Noise Level Modified DNL DNL

7. Frequency Character of the NoiseWhy is some noise more annoying?

8. How does Noise Effect People? • Hearing Loss • Speech Interference • Sleep Interference • Classroom Learning • Physiological Response • Annoyance

9. Speech Interference

10. Sleep Interference

11. How does Noise Effect People? • Hearing Loss • Speech Interference • Sleep Interference • Classroom Learning • Physiological Response • Annoyance

12. Annoyance (FAA Research)

13. Annoyance (NPS Research)

14. Factors that Affect Individual Annoyance to Noise

15. Factors that Affect Noise Source Levels • Engine technology • Aircraft technology • Rotor or propeller design • Power Level • Prop Pitch • Speed

16. 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

17. Temperature and Humidity

18. AVI 2

19. 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

20. Brotherhood Park Helicopter Events

21. Long Duration Helicopter Events Bonnie Brae

22. Character of Noise

23. 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

24. Douglas 5th Float Plane Events

25. Character of Noise

26. 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

27. 1994 vs. 2000 Noise • Changes between 1994 and 2000 • Increased Operations • Improved Flight Paths • Quieter Technology

28. 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