An Efficient Delayless Sub-band Filtering for Adaptive Feedback Compensation in Hearing Aid

摘要

Acoustic feedback, or signal leakage between the loudspeaker and microphone of hearing aids, creates some irritations to the users of these devices and degrades the performance of the hearing aids. Among various methods proposed to cancel the negative effect of acoustic feedback, Instrumental Variable Method Adaptive Feedback Canceller (IVM-AFC) has shown superb performance. IVM-AFC exploits two kinds of adaptive filters to pre-filter the signals and to estimate the feedback path transfer function, respectively. This AFC method typically uses Partitioned Block Frequency Domain Normalized Least Mean Square (PBFD- NLMS) algorithm for the feedback path estimation. In this paper, two alternative algorithms are introduced in addition to PBFD-NLMS. One is Discrete Fourier Transform Multi-Delay block Frequency domain NLMS (DFT-MDF-NLMS) algorithm not used for this application before. The other one is a new delayless sub-band filtering algorithm. The algorithms are evaluated using speech as the input of hearing aid. Based on the experimental results, the new sub-band filtering method possesses low computational complexity and high capability of tracking the changes in the feedback path.