Evaluation of Military Hearing Protection Devices in a Simulated Aircraft Carrier Soundscape

Abstract

Auditory situation awareness, including the ability to localize sound sources rapidly and accurately, is essential for military personnel operating in complex, high-risk environments. Effective auditory localization enables service members to detect threats, maintain spatial orientation, and communicate vital information, particularly under conditions where visual cues are limited. Unfortunately, the same headsets service members rely on to protect their hearing also convey deleterious effects on localization and situation awareness. Oftentimes, service members choose to improperly fit hearing protection, or forgo it entirely, to maintain situation awareness and better protect themselves against life-threatening hazards in the environment. This study evaluated two newly developed systems — the Frontier 1 and Frontier 2 — against four commonly used military hearing protection devices (HPDs) and the open ear within simulated aircraft carrier flight deck and room ambient conditions. Fourteen normal-hearing participants completed a series of auditory localization tasks using the Portable Auditory Localization Acclimation Test (PALAT) system, which measured absolute accuracy, ballpark accuracy, response time, front-back reversal errors, and left-right reversal errors. Subjective measures of confidence, comfort, and acceptability were also assessed. A full-factorial, repeated-measures design with counterbalanced condition order was employed. Differences in mean performance metrics were analyzed using linear mixed-effects models for omnibus testing and paired-samples t-tests with Holm-Bonferroni corrections for post hoc pairwise comparisons. Results indicated that headset type significantly influenced localization performance and subjective ratings, with several active HPDs outperforming passive devices in preserving situation awareness. Performance differences were environment-dependent, emphasizing the challenges of protecting hearing without degrading spatial awareness in noisy operational settings. Furthermore, despite employing active noise cancellation (ANC) technology, the Frontier 2 did not perform significantly better than its counterpart. This suggests that electronically-modulated HPDs, which include both pass-through and ANC, do not necessarily afford users significantly different performance in similar environments. Findings support the adoption of advanced HPDs to enhance auditory situation awareness, preserve mission effectiveness, and promote compliance with hearing protection protocols in naval aviation environments.