Auditory Localization Performance with Gamma Integrated Eye and Ear Protection

Auditory localization performance was assessed for participants wearing the gamma integrated eye and ear protection (IEEP), a prototype tactical communications and protection system that also provides eye protection. Testing was conducted using one of the auditory localization measurement methods recently proposed as a standard by the Department of Defense Hearing Center of Excellence. Participants used a laser pointer to indicate the perceived location of a sound presented from 1 of 36 loudspeakers. This task was completed both with ears unoccluded (no IEEP) and with the IEEP. Pink noise was used for the sound stimuli (either 250 ms or 4000 ms), randomly roved from 60 to 75 dBA. Localization accuracy was measured as the horizontal angular difference between the target loudspeaker location and the participants estimate. The data were analyzed taking into account individual ability, as well as the known effects of sound source azimuth and stimulus duration. After taking these known effects into account, we concluded the IEEP did not significantly change overall localization ability. However, it did have a small, but significant, effect on accuracy for the short-duration (250 ms) stimuli due to an increase in reversals (front-back confusions).