Evaluation of Auditory Characteristics of Communications and Hearing Protection Systems (C&HPS)
Part III  Auditory Localization

Report No. ARL-TR-6560
Authors: Paula P. Henry
Date/Pages: August 2013; 40 pages
Abstract: Devices that provide hearing protection, situational awareness and radio communications are often referred to as Communications and Hearing Protection Systems (C&HPS). Soldiers use these systems to maintain auditory awareness within their environment, communicate with their team members and protect their hearing. Each of the three features of select C&HPS (hearing protection, speech communication and situational awareness) were independently evaluated by the U.S. Army Research Laboratory (ARL). This report is the third in a series of three and focuses on the auditory localization performance obtained from two commercially available C&HPS: Nacre QuietPro and Silynx QuietOps. These two systems were selected from three C&HPS evaluated for attenuation characteristics in the first report and speech intelligibility in the second report; the third system provided insufficient attenuation to be included. Results of the auditory localization testing indicated that both C&HPS negatively affected auditory localization accuracy performed in background noise, but the observed decrement was not significantly different between the two systems. Evidence from objective measures of the systems such as directivity, calculation of interaural level differences (ILDs), and the measurement of input/output functions indicate that changes in binaural intensity difference cues were the primary factor driving the reduction in performance.
Distribution: Approved for public release
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Last Update / Reviewed: August 1, 2013