Free-field sound localization with nonlinear hearing protection devices
Kimberly B. Lukas, William A. Ahroon · The Journal of the Acoustical Society of America · 2006
Hearing enhancement and protection devices are being developed for both civilian and military markets that permit the wearer to maintain an awareness of the ambient sound environment and permit face-to-face communications while still protecting the user from high-level impulse noises or blast waves from, for example, handguns, rifles, and shotguns. The impulse noise protection for these devices can range from less than 9 dB peak pressure reduction to reductions of more than 40 dB peak. There has been little research, however, on the ability to use binaural cues to localize sound with such devices. An experiment to evaluate the ability of normal-hearing listeners to localize broadband noise bursts while wearing various nonlinear hearing enhancement and protection systems was conducted in an anechoic environment. Subjects were asked to localize a 60-dB SPL, 200-ms broadband noise burst from a speaker in 1 of 12 different azimuth locations (0 to 330 deg in 30-deg steps) and five different elevations (0, ±15, ±30 deg). The azimuth and elevation errors were measured for each device using circular statistical techniques. Front/back reversals were corrected. The results show a 15- to 20-deg degradation in the wearer’s ability to localize sound when using these hearing protectors.