Noise reduction for hearing aids using digital signal processing

点击翻译按钮获取中文摘要

1. Algorithm for noise reduction An algorithm for reducing stationary/nonstationary environmental noise has been developed and has been verified via computer simulation. Moreover, total noise reduction system has been constructed using signal processing system. For ebvironmental noise reduction, an adaptive beamforming technique was combined with conventional fixed beamformer to obtain robust attenuation for not only stationary noise but also nonstationary noise. On the other hand, for reducing howling, adaptive feedback canceler was introduced.2. Evaluation The system developed has been applied to real environmental noise and was evaluated in terms of the amount of noise reduction and other issues. The results can be summarized as follows : As for the environmental noise, directional noise with large power was reduced by more than 20 dB,while nondirectional noise such as reverberation is also reduced by 10 dB.As for the howling, howling margin increased by 20 dB.3. Improvement in Speech Intelligibility Noise reduction system has been applied to the speech corrupted by noise, and the listening test was conducted. The results can be summarized as follows : As for the environmental noise reduction, the speech intelligibility was improved from 50 % to 70 % by introducing the proposed system. As for the howling cancellation, periodic signals such as voiced speech is corrupted by the conventional adaptive feedback canceler. However, use of frequency compressor together with adaptive feedback canceler as proposed in our system yields little corruption and no effect on speech intelligibility.