A Comparison of Frequency-invariant Beamforming Algorithms for Hearing Aids: Differential Microphone-based Beamformers and the Broadband Beamformer

Abstract

Purpose Recently, some research groups have suggested thepossibility of using the broadband beamformer (BBF)algorithm for hearing aid applications. However, there havebeen no previous reports to have quantitatively evaluatedthe relative performance between conventional differentialmicrophone (DM)-based frequency-invariant beamformingalgorithms and the broadband beamformer.Methods In this study, we evaluated the performance ofDM-based beamformer algorithms and the BBF algorithm invitro using the four objective indices of signal-to-noise ratio(SNR), perceptual evaluation of speech quality (PESQ),noise distortion (Cbak) and weighted spectral slope (WSS) ina non-reverberant environment.Results The experimental results showed that the DM-basedalgorithms were superior in terms of SNR, WSS and Cbak,and the BBF algorithm was superior in terms of PESQ.Conclusions Considering the limited performance of hearingaid processors and the experimental results, DM-basedfrequency-invariant algorithms with a first-order compensation filter are more feasible for real hearing aids. However,additional in vitro and clinical evaluations are required to moreaccurately verify the clinical feasibility of these algorithms.