noise_issues - Noise Issues in Aviation Planning CEE 5614...

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Copyright - Antonio A. Trani 1 of 30 Noise Issues in Aviation Planning CEE 5614 Analysis of Air Transportation Systems Dr. Antonio A. Trani Associate Professor of Civil Engineering Virginia Tech
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Copyright - Antonio A. Trani 2 of 30 What is Noise? Many definitions of noise exist “Unwanted sound” “Any acoustic signal that detracts from the primary task in hand” Aviation noise is the net result of aircraft flyovers as well as any other activity at the airport that produces unwanted sounds Auxiliary Power Units (APU) Boilers and Chillers Automobile activity
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Copyright - Antonio A. Trani 3 of 30 Is Noise Important? One the most limiting factors in airport and aviation infrastructure expansion Many communities resent noise and thus limit airport and airspace growth activities Some airports (like Haneda in Japan and Munich in Germany) have taken 30 years to build new runways due to noise concerns In the U.S. noise is a big factor as well. Many airports face strict scrutiny due to noise-related complaints
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Copyright - Antonio A. Trani 4 of 30 Measuring Noise Noise is usually measured in Sound Pressure Level units (SPL - in Bels or decibels - dB) Annoyance due to noise is measured in Noys (see any human factors book for more information) Complex metrics have been developed to estimate the annoyance of aviation noise (flyovers and airport operations) + DNL - Average Day-Night Sound Level + CNEL - Community Noise Exposure Level + NEF - Noise Exposure Forecast
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Copyright - Antonio A. Trani 5 of 30 Definition of Sound Pressure Level Definition of SPL (1) where: is the sound pressure level (in dBA) is the pressure generated by the noise in question is the minimum audible pressure (0.002 Dyn/cm 2 ) SPL 20 P P 0 ---- log = SPL P P o
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Copyright - Antonio A. Trani 6 of 30 Human Frequency Response to Noise Humans perceived noise at various frequencies according to the following notional response curve SPL (dB) 20 1000 20000 Frequency (Hz) Scale C Scale A Human Response
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Copyright - Antonio A. Trani 7 of 30 Human Response A weighing scale assigns arbitrary values of SPL across the frequency domain Typically band centers for each weight are: (31.5, 63, 125, 250,500,1000, 2000, 4000, 8000, 16000 Hz) A single value of SPL can then be derived that includes all bands Of all possible weighting scales across frequency usually the A-scale is employed in aviation noise - labeled as dBA
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Copyright - Antonio A. Trani 8 of 30 Noise Attenuation Models Several theoretical and empirical models have been developed Linear Inverse-law Model (LIM) Power Inverse Models (PIM) Empirically derived models (such as those used in aviation noise computer applications) Most attenuation models correct for atmospheric effects (temperature and pressure)
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Copyright - Antonio A. Trani 9 of 30 LIM Model (2) where: is the reference distance (typically 15 m. or 50 ft.),
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This note was uploaded on 12/31/2011 for the course CEE 5614 taught by Professor Staff during the Fall '10 term at Virginia Tech.

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noise_issues - Noise Issues in Aviation Planning CEE 5614...

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