Multi-Microphone Noise Reduction for Hearing Assistive Devices

Abstract

The paramount importance of good hearing in everyday life has driven an exploration into the improvement of hearing capabilities of (hearing impaired) people in acoustic challenging situations using hearing assistive devices (HADs). HADs are small portable devices, which primarily aim at improving the intelligibility of an acoustic source that has drawn the attention of the HAD user. One of the most important steps to achieve this is via filtering the sound recorded using the HAD microphones, such that ideally all unwanted acoustic sources in the acoustic scene are suppressed, while the target source is maintained undistorted. Modern HAD systems often consist of two collaborative (typically wirelessly connected) HADs, each placed on a different ear. These HAD systems are commonly referred to as binaural HAD systems. In a binaural HAD system, each HAD has typically more than one microphone forming a small local microphone array. The two HADs merge their microphone arrays forming a single larger microphone array. This provides more degrees of freedom for noise reduction. The multi-microphone noise reduction filters are commonly referred to as beamformers, and the beamformers designed for binaural HAD systems are commonly referred to as binaural beamformers.