On the improvement of acoustic feedback cancellation in hearing-aid

This paper presents a decorrelation technique to improve the performance of acoustic feedback cancellation in hearing aids, particularly for the continuous adaptation approach. It is proposed that the input and the output signals of the hearing aids are decorrelated via the use of higher-order time-varying allpass filters in order to adequately decorrelate the signals with as little degradation of the quality of the output signal of the hearing aids as possible. Simulation results are presented based on real speech signals and supported by subjective listening tests.

I. INTRODUCTION

Acoustic Feedback Cancellation (AFC) is necessary for hearing aids in order to eliminate the howling perceived by the users. This is because the amplified signal at the output of the hearing aids is also sent back to the microphone at the input terminal of the devices via the air vent. The howling effect becomes more severe to the users especially when the gain of the devices is large. Thus, the dynamic range of the hearing aids is limited due to this acoustic feedback problem.