Analysis of Noise in US Army Aircraft.
Final rept. Jul 76-Mar 78,
VOUGHT CORP ADVANCED TECHNOLOGY CENTER INC DALLAS TEX
Pagination or Media Count:
Tape recordings were made of acoustical and electrical noise in the crew compartments and on the interphone lines of 7 models of U.S. Army aircraft, during flight operations. The data were analyzed to determine noise and speech levels in the communication channel, especially at crew members ears. Calculations were then performed to estimate hearing damage risk and estimate the intelligibility of speech. The purpose of the project was to identify harmful noise levels and sources in the communication channel and to make recommendations for reducing such noise. At frequencies below about 1000 Hz, noise in the communications channel is due primarily to ambient noise which enters the circumaural earcup through leaks between the cushion and the head. Above 1000 Hz, the noise in the channel is due primarily to ambient noise which is picked up by the microphone and transmitted to the earphone. The hearing damage risk calculations show that less than 1 of air crewmen would suffer more than a 10 dB hearing loss at speech frequencies after 10 years of flight duty. This is based on 4 hours per day of flight. Typical inter- and intra- aircraft speech intelligibilities were predicted to be greater than 95.
- Radio Communications