Work is proposed to develop an advanced hearing protector that combines maximal attenuation of ambient sounds with signal processing that extracts the most important components of the sound field for controlled presentation to the user. By processing the signals from a microphone array mounted on the headband of the hearing protector, this device enhances desired signals from a specified """"""""look about direction relative to signals from other directions, allowing face-to-face acoustic communication in many high-noise environments where it would be impossible otherwise. In addition, the signal processing allows the preservation of sound localization ability. Work in Phase I developed implementations of array-processing algorithms on a portable DSP processor and evaluations of their impact on listeners' sound localization and speech reception performance. The goal of Phase II -- a fully-specified prototype device ready for manufacturing -- will be achieved through work in four areas: 1) development of algorithms for directional gating and automatic spectral shaping; 2) development of the capability to deliver acoustic stimuli to the ear canals with combined hearing protection from muffs and insert plugs; 3) active noise reduction in the combined-protection mode for maximal sound reduction; and 4) electronic and mechanical design to allow the microphones and circuitry to be mounted entirely on the headband of a muff-style hearing protector.
The hearing protector/communication headset being developed will be of use in high-noise environments where it is necessary to have both hearing protection and the abilities to communicate face-to-face and to monitor sounds. Some aspects of the projects will result in improved communication headsets, devices that deliver a communication _signal to the user without acoustic sensing of the environment.
