HEaDS-UP Phase IVAssessment: Headgear Effects on Auditory Perception

Report No. ARL-TR-7203
Authors: Angelique A Scharine
Date/Pages: February 2015; 42 pages
Abstract: Two modular helmet systems, consisting of helmet, eye, and mandible protection plus tactical communications via earmuffs (EMs), earplugs (EPs), or double hearing protection, developed under the Helmet Electronics and Display System-Upgradeable Protection program were evaluated for their effects on auditory perception. Measures of passive directional attenuation were made for the helmets alone, hearing protection alone, and in combination. The situation awareness (SA) microphones of the communications system compressed noise transmission when ambient levels exceeded 85 dB (A) so that at 110 dB (A) the noise level under the EPs was only 88 dB (A) for the highest microphone setting. For EMs, attenuation was limited to approximately 18.5 dB (A) of passive protection with additional amplification caused by the ear canal; therefore, with the microphones on the highest setting, the level under the EM at 110 dB (A) was 110 dB (A). Impulse noise attenuation for the systems was measured by presenting impulses at peak levels of 150 and 171 dB with the SA microphones turned off, on low, and on high. EPs, EMs, and double hearing protection provided impulse noise protection equivalent to the passive attenuation of the hearing protectors when the SA microphones were on.
Distribution: Approved for public release
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Last Update / Reviewed: February 1, 2015