Beamformer performance limits in monaural and binaural hearing aid applications

This paper investigates the performance limits of beamforming algorithms in monaural and binaural multi-microphone hearing aids. Directional microphones and minimum variance distortionless response (MVDR) beamformer designs are reviewed in the context of hearing aids. A general binaural filter-and-sum beamformer structure is described based on combining microphone signals from right and left hearing aids. The monaural and binaural algorithms are evaluated with respect to directivity pattern, directivity index, and noise gain. Simulation results show that for a frontal source signal, a binaural beamformer is capable of increasing the directivity by approximately 3 dB compared to a single-array beamformer, but with no increase in the noise gain.