ICSV26

Prevention of noise-induced hearing loss via hearing protection devices (HPDs), together with con-comitant preservation of one's auditory situation awareness (ASA) and vigilance to the surrounding acoustic environment, is critical. Examples include construction workers who wear electronic ear-muffs but must hear backup alarms, emergency vehicle drivers who need hearing protection from the vehicle's siren but must also hear car horns and communications, and military personnel who wear gunfire-noise-protective headsets but must hear certain signals and speech. This paper re-views several ASA experiments on "augmented" HPDs, which rely on either passive (i.e., dynamic acoustic "valves" and filter) or active (i.e., battery-powered electronic) technologies, that are in-tended to provide "pass-through" hearing capability with concomitant hearing protection. Over the past decade, several in-field and in-lab experiments at Virginia Tech have demonstrated that certain augmented HPDs and Tactical-Communications-and-Protective-Systems (TCAPS) in fact do not provide natural hearing or "transparency," and have deleterious effects on ASA. Experimental stimuli have included vehicular warning alarms, military-relevant signals and other signatures of broadband, low-frequency, and high-frequency content. Measures of ASA performance have in-cluded: hearing threshold at detection, accuracy and response time in recognizing/identifying and localizing signals, and intelligibility of communications. Based on these experiments, an objective, repeatable test battery was developed for evaluating HPD and TCAPS effects on the ASA tasks of: Detection, Recognition/Identification, Localization (azimuth and frontal elevation), and COMmu-nication, known as "DRILCOM." Example results from the ASA testing using various signals are covered. Also, the interaction effects of HPD attenuation with the low-frequency interaural time difference (ITD) cues and high-frequency interaural level difference (ILD) cues that are so critical to localization are covered. It is postulated that standardized ASA testing of augmented HPDs and TCAPS, in similar fashion to commonplace and standardized attenuation testing, should be done before devices are deployed on personnel in dangerous environments. 

NOTE: This work received the "Safe in Sound Award for Innovation in Hearing Conservation," awarded by the National Institute for Occupational Safety and Health (NIOSH) in February, 2016. See: http://www.safeinsound.us/winners.html