Effects of binaural electronic hearing protectors on localization and response time to sounds in the horizontal plane

The effects of electronic hearing protector devices (HPDs) on localization and response time (RT) to stimuli were assessed at six locations in the horizontal plane. The stimuli included a firearm loading, telephone ringing and .5-kHz and 4-kHz tonebursts presented during continuous traffic noise. Eight normally hearing adult listeners were evaluated under two conditions: (a) ears unoccluded; (b) ears occluded with one of three amplitude-sensitive sound transmission HPDs. All HPDs were found to affect localization, and performance was dependent on stimuli and location. Response time (RT) was less in the unoccluded condition than for any of the HPD conditions for the broadband stimuli. In the HPD conditions, RT to incorrect responses was significantly less than RT to correct responses for 120 degrees and 240 degrees , the two locations with the greatest number of errors. The RTs to incorrect responses were significantly greater than to correct responses for 60 degrees and 300 degrees , the two locations with the least number of errors. The HPDs assessed in this study did not preserve localization ability under most stimulus conditions.