Quantitative Evaluation of the Performance of Monaural FDSI Beamforming Algorithm using a KEMAR Mannequin

Abstract: To enhance the speech perception of hearing aid users in noisy environment, most hearing aid devicesadopt various beamforming algorithms such as the first-order differential microphone (DM1) and the two-stage direc-tional microphone (DM2) algorithms that maintain sounds from the direction of the interlocutor and reduce the ambi-ent sounds from the other directions. However, these conventional algorithms represent poor directionality abilityin low frequency area. Therefore, to enhance the speech perception of hearing aid uses in low frequency range, ourgroup had suggested a fractional delay subtraction and integration (FDSI) algorithm and estimated its theoretical per-formance using computer simulation in previous article. In this study, we performed a KEMAR test in non-rever-berant room that compares the performance of DM1, DM2, broadband beamforming (BBF), and proposed FDSIalgorithms using several objective indices such as a signal-to-noise ratio (SNR) improvement, a segmental SNR (seg-SNR) improvement, a perceptual evaluation of speech quality (PESQ), and an Itakura-Saito measure (IS). Experi-mental results showed that the performance of the FDSI algorithm was −3.26-7.16 dB in SNR improvement, −1.94-5.41 dB in segSNR improvement, 1.49-2.79 in PESQ, and 0.79-3.59 in IS, which demonstrated that the FDSI algo-rithm showed the highest improvement of SNR and segSNR, and the lowest IS. We believe that the proposed FDSIalgorithm has a potential as a beamformer for digital hearing aid devices.Key words: hearing aids, directional microphone, beamforming