Accession Number : ADA301097

Title :   Lateral Attenuation of Aircraft Flight Noise.

Descriptive Note : Final rept. Aug 82-Dec 84,

Corporate Author : BBN LABS INC CANOGA PARK CA

Personal Author(s) : Bishop, Dwight E.

PDF Url : ADA301097

Report Date : MAR 1985

Pagination or Media Count : 34

Abstract : This report reviews models for calculating the lateral attenuation of aircraft flight noise, in particular, the change in attenuation for different-elevation angles varying from aircraft directly overhead (900 elevation angle) to a zero elevation angle. Sets of noise spectrum-dependent lateral attenuation values derived from theory and from experimental (AMRL) flight measurements were applied to sets of different aircraft noise spectra to determine A-level differences with elevation angle. The lateral attenuation based on the theoretical model showed near negligible attenuation above 50 elevation angle. The lateral attenuation based on the experimental data showed appreciably greater attenuation, but still less attenuation than the SAE model currently incorporated in the Integrated Noise Model (INM) aircraft noise computer program. Based on the experimental curves, a new generalized transition model was developed and is recommended as a replacement for the current HISEMP lateral transition algorithm. (AN)

Descriptors :   *ACOUSTIC ATTENUATION, *AIRCRAFT NOISE, COMPUTER PROGRAMS, MATHEMATICAL MODELS, ALGORITHMS, TURBOFAN ENGINES, TURBOPROP ENGINES, SOUND TRANSMISSION, TAKEOFF, JET FIGHTERS, JET TRANSPORT AIRCRAFT, ELEVATION, RANGE(DISTANCE), FLIGHT PATHS, ACOUSTIC DATA, SOUND PRESSURE, AIRCRAFT LANDINGS, ACOUSTIC IMPEDANCE, ACOUSTIC REFLECTION.

Subject Categories : Acoustics
      Attack and Fighter Aircraft
      Transport Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE