Accession Number : ADA301337

Title :   Study of Lateral Excess Sound Attenuation as Determined from Far Part 36 Aircraft Noise Certification Measurements.

Descriptive Note : Technical rept.,

Corporate Author : BOLT BERANEK AND NEWMAN INC CANOGA PARK CA

Personal Author(s) : Bishop, Dwight E. ; Beckmann, Jane M.

PDF Url : ADA301337

Report Date : JUL 1980

Pagination or Media Count : 58

Abstract : This report presents information on the variation of the lateral excess attenuation as a function of elevation angle. Lateral excess attenuation represents the differences between the noise levels measured directly underneath the aircraft and to the side of the aircraft, after adjustment for differences in distance and air absorption. This information was developed from analysis of "takeoff" and "sideline" noise data acquired during FAR 36 civil aircraft noise certification tests. Curves showing the variation of lateral excess attenuation as a function of elevation angle are shown for individual one-third octave bands from 50 Hz to 2000 Hz and for maximum A-levels and maximum perceived noise levels curves are presented for four aircraft: Lockheed Hercules C-l30H, Gates Learjet Model 2ND with conical nozzle, Gates Learjet Model 2ND with daisy nozzles and shrouds, and Rockwell International Sabre- liner NA265-65. Due to differences in the distribution of noise level measurements versus elevation angle among tests, good coverage of elevation angles was obtained only for the C-l30H measurements and by combining data for the two Gates Learjet 2ND tests.

Descriptors :   *ACOUSTIC MEASUREMENT, *ACOUSTIC ATTENUATION, *TRANSPORT AIRCRAFT, *AIRCRAFT NOISE, ANGLES, COMPUTATIONS, AIR, GATES(CIRCUITS), VARIATIONS, LEVEL(QUANTITY), NOZZLES, ATTENUATION, COVERINGS, ABSORPTION, ELEVATION, CONICAL NOZZLES.

Subject Categories : Transport Aircraft
      Acoustics
      Noise Pollution and Control

Distribution Statement : APPROVED FOR PUBLIC RELEASE