Warflghter Auditory Situation Awareness: Locating the Shooter with and without Hearing Protection

摘要

A controlled field experiment was conducted using a specially prepared, partially forested remote rural site to ascertain listeners' aural performance in locating the azimuthal direction of actual gunshots (blank cartridges) from hidden "snipers." Subjects were required to detect and localize the gunshots, which corresponded to eight shooter positions in a 360-degrees radius around their stationary listening position, by vocalizing target sign numbers. The study had five listening conditions: four military hearing protection/enhancement devices (HPEDs), and an open-ear (i.e., no HPED) condition presented in a randomized sequence with two noise levels, rural resting ambient of 45-50 dBA, and 82 dBA military diesel truck high idle engine noise. Five objective measures of localization accuracy, and an additional measure of response time for eight shooter positions, were measured for nine normal hearing and four impaired hearing participants. Statistical analysis showed worse accuracy and response time performance with the electronic earmuffs (Peltor Com-Tac Ⅱ~(TM)) than with the other tested HPEDs (Etymotic EB 1 and EB 15, both set to the Lo gain positions and 3M Combat Arms™ earplug in its level-dependent, "open" position). Performance with all HPEDs was worse than that with the open ear (except on right-left confusions, in which the Com-Tac Ⅱ earmuff stood alone as worst) and in response time, for which the EB 1 was equivalent to the open ear. There was no significant main effect of noise on performance. Hearing impairment increased right-left confusions. Subjective ratings generally corroborated objective localization performance. These results show the importance of human factors input to HPED design, as well as application of realistic auditory tests relating to situational awareness of the user, especially for dangerous situations such as sniper localization. These results have certain applications for the military as well as law enforcement, first responders, and recreational firearm users.