The Effect of Helicopter Noise on Communication and Hearing.
Research and development technical rept.,
ARMY ELECTRONICS COMMAND FORT MONMOUTH N J
Pagination or Media Count:
STEM INTELLIGIBILITY ARE SERIOUS ONES. The effort described by this report is aimed at reducing the sound pressure levels at the aviators ears while maintaining high intelligibility and quality in the communication system. The overall problem is first defined. The noise levels inside all areas of the CH-47 were found to exceed the hearing damage risk criteria set forth by the Surgeon General. Even with hearing protectors, the aviator is limited to the time he may fly without undue risk to his hearing. The electrical characteristics of the communication system were determined. Non-linear frequency responses of the microphone and earcup were detected. These resonances cause emphasis of those frequencies in which the ear is most sensitive. The poor noise cancelling ability of the M-87 microphone at high frequencies cause low signal to noise ratios in the communication system. An intelligibility vs. in-ear dBA level study was run to evaluate the potential success of an ideal perfect noise cancelling microphone and other microphone modifications.
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