Hearing and sound source identification with protective headwear.
This study investigated the effect on hearing, sound attenuation, and sound source identification of a prototype neck and two prototype mandible guards attached to a combat helmet. Ten male subjects participated. Free-field hearing thresholds were measured from 250 Hz to 8,000 Hz with the head bare and fitted with the helmet alone and with the guards. Sound source identification was assessed using a horizontal array of eight loudspeakers surrounding the subject. The stimulus was a 75-dB SPL, 300-ms noise burst. Neither the helmet worn alone or with the guards affected hearing or provided significant sound attenuation. The helmet combinations resulted in a significant decrease in sound source identification, of 11.6%. This was due to diminished accuracy for loudspeakers close to the interaural axis of the head. The neck guard induced a frontal bias for these positions. This error pattern is not likely to interfere with localization during combat.
Defence Research and Development Canada - Toronto, PO Box 2000, 1133 Sheppard Avenue West, Toronto, Ontario, Canada M3M 3B9.
Sharon M
SM
Abel
Michel B
MB
DuCharme
Dan
D
van der Werf
D000328:Adult; D001309:Auditory Threshold; D002170:Canada; D004867:Equipment Design; D006260:Head Protective Devices; D006309:Hearing; D006801:Humans; D008297:Male; D008889:Military Personnel; D013017:Sound Localization