Binaural Linearly Constrained Minimum Variance Beamformer for Hearing Aid Applications

Abstract:
In many cases hearing impaired persons suffer from hearing loss in both ears, necessitating two hearing apparatuses. In such cases, the applied speech enhancement algorithms should be capable of preserving the, so called, binaural cues. In this paper, a binaural extension of the linearly constrained minimum variance (LCMV) beamformer is proposed. The proposed algorithm, denoted binaural linearly constrained minimum variance (BLCMV) beamformer, is capable of extracting desired speakers while suppressing interference speakers. The BLCMV maintains the binaural cues of both the desired and the interference sources in the constrained space. The ability of preserving the binaural cues makes the BLCMV beamformer particularly suitable for hearing aid applications. It is further proposed to obtain a reduced complexity implementation by sharing common blocks in both sides of the hearing aid device. The performance of the proposed method, in terms of imposed distortion, interference cancellation and cue preservation, is verified by an extensive experimental study using signals recorded by a dummy head in an actual room. Index Terms — Binaural cues, array signal processing, LCMV beamforming, hearing aids, noise reduction.