Augmented warning sound detection for hearing protectors.

Perception of warning sounds, such as vehicle backup alarms, is reduced when hearing protection devices (HPDs) are worn. A cross-correlation approach is employed to detect a pre-selected warning sound and enable it to bypass the attenuation of the HPD while still attenuating the environmental noise. Computer simulation shows that the algorithm can detect the specified alarm at signal-to-environmental-noise ratios as low as -30 dB. Human subject testing of the algorithm, implemented on a modified commercial HPD, confirms the minimum detection threshold obtained in simulation, and demonstrates a 7 dB improvement in detection threshold compared with the unmodified HPD.