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 the possibility of using the broadband beamformer (BBF) algorithm for hearing aid applications. However, there have been no previous reports to have quantitatively evaluated the relative performance between conventional differential microphone (DM)-based frequency-invariant beamforming algorithms and the broadband beamformer. Methods: In this study, we evaluated the performance of DM-based beamformer algorithms and the BBF algorithm in vitro 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) in a non-reverberant environment. Results: The experimental results showed that the DM-based algorithms 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 hearing aid processors and the experimental results, DM-based frequency-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 more accurately verify the clinical feasibility of these algorithms.