The effect of firefighter personal protective equipment on auditory thresholds

Communication on a fire scene is essential to the safety of firefighters. Not only to be able to hear and understand radio chatter, but also alarm signals used on the fireground. One such alarm is the Personal Alert Safety System (PASS) device. This device is used to help locate a downed firefighter. One part of this complex problem is the effect of the protective equipment (helmet, eye protection, hood, coat) on hearing. Previous findings have shown the effect of this protective equipment on head related transfer functions using a KEMAR. [Suits et al. (2013, June). Paper presented at the International Congress on Acoustics, Montreal, Canada] The physical acoustic measurements showed a change in the signal that would reach the tympanic membrane. To relate the findings of the physical measurements to human reactions, the change in auditory threshold caused by wearing the personal protective equipment was measured. The changes seen in the physical acoustics measurements caused the auditory threshold of the subjects to increase at higher frequencies. The measured increases at 3000 Hz, 4000 Hz, and with an example PASS signal were between 5 and 10 dB. [Work supported by U.S. Department of Homeland Security Assistance to Firefighters Grants Program.]