Effects of the Advanced Combat Helmet (ACH) and Selected Communication and Hearing Protection Systems (C&HPSs) on Speech Communication: Talk-Through Systems

Report No. ARL-TR-4078
Authors: Rachel A. Weatherless; Rhoda M. Wilson; Lamar Garrett; Tomasz R. Letowski; Mary S. Binseel
Date/Pages: April 2007; 35 pages
Abstract: Communication in military settings must be clear and understandable to avoid possible fatal accidents and mistakes. Speech intelligibility is the overall quality of speech that makes it comprehensible. Intelligibility of speech depends on the properties of the talker, transmission channel, and the listener. The purpose of the reported study was to evaluate intelligibility of speech provided by five communication and hearing protection systems (C&HPSs) operating in talk-through mode. The systems evaluated in this study were the Product Improved-Combat Vehicle Crewman?s (PI-CVC) helmet, Bose Improved Tactical Headset (ITH), Mine Safety Appliances-Sordin ?Gen II? headset (Gen II), Communications Enhancement and Protection System (CEPS), and Combat Arms Earplugs (CAE). All systems except for the first one were worn with the Advanced Combat Helmet (ACH). The baseline conditions for assessing the communication data were bare head and the ACH worn alone. Results show that the ACH only, PI-CVC, and Gen II conditions provided significantly better speech intelligibility than the CAE and CEPS for the listeners participating in the study. Performance data for the ITH condition fell between the two groupings. Overall, the earplug-based communication systems (CAE and CEPS) resulted in lower performance and larger data variability than the earmuff-based systems. This larger variability could be attributed to poor repeatability in earplug insertion, which may be limited through more extensive training.
Distribution: Approved for public release
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Last Update / Reviewed: April 1, 2007