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Bone Conduction as a Viable Alternative to Current Communications Systems in Fighter Cockpits.

INTRODUCTION
Effective voice communication is essential when operating aircraft. Because of the loud operating environment in fighter cockpits, it has been a challenge to provide effective communication while simultaneously protecting the hearing sense. The objective of this study was to determine the feasibility of using bone conducting transducers (BCT) in place of legacy communications systems in fighter cockpits.


METHODS
A military flight helmet was modified and outfitted with BCT and air-conducting speakers. BCT were independently tested against air-conducting speakers using a clinical audiometer under three conditions: without earplugs, with earplugs, and with earplugs in the presence of 100-dB broad-spectrum noise. Three test subjects were given an audiological examination using tones of varying intensity ranging from 100 Hz to 8000 Hz. The lowest hearable intensity indicated by button press was recorded for each frequency.


RESULTS
In the presence of 100-dB ambient noise, bone conducting transducers performed better than air-conducting speakers at all frequencies. Hearability of BCT by audiogram was, on average, 10-20% lower intensity (dB) than air-conducting speakers.


DISCUSSION
Currently, USAF pilots wear two layers of hearing protection; i.e., the helmet's integrated earcup and some form of ear plug (e.g., foam earplug or custom-molded earbud). Our results suggest that bone conducting audio transducers may be better for layered hearing protection than air-conducting speakers when used with foam earplugs. Given the cost, complexity, and non-interoperability of custom-molded earphones, helmet-integrated bone conducting transducers and foam earplugs may be a better option for sustained airborne operations.Bradke BS, White Z, Poston J. Bone conduction as a viable alternative to current communications systems in fighter cockpits. Aerosp Med Hum Perform. 2018; 89(10):927-930.