SUPPRESSION OF ACOUSTIC FEEDBACK IN HEARING AIDS USING DUAL ADAPTIVE FILTERING
Date
2015-11
Authors
Journal Title
Journal ISSN
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Publisher
Pulchowk Campus
Abstract
Acoustic feedback is a major problem in most of the hearing aid users. This feedback
corrupts the speech signal and causes instability. In this thesis, a new solution
approach for the suppression of continuous acoustic feedback in the digital hearing
aids has been dealt with. In this method, two adaptive filters work in tandem to
mitigate the acoustic feedback. The error signal of the first adaptive filter is used as a
desired response for the second adaptive filter and the filter weights are adapted using
Normalized Least Mean Square (NLMS) and modified NLMS algorithms which is a
novel approach presented in this thesis. Due to the correlation between input and
desired response, a bias is found in the adaptive filter‟s estimate of the feedback path.
An appropriate delay is inserted at the output of the hearing aid to reduce this bias.
Based on this delay based processing, a new strategy is proposed to exchange the
weights between the two adaptive filters. Unlike previous techniques, initial weights
of the adaptive filters are chosen other than either 1‟s or 0‟s such that faster
convergence is achieved. Computer simulations are performed and the results verify
the effectiveness of the proposed method.
Description
Acoustic feedback is a major problem in most of the hearing aid users. This feedback
corrupts the speech signal and causes instability.
Keywords
Hearing Aids, Adaptive Filters, Acoustic Feedback, NLMS
Citation
MASTER OF SCIENCE IN INFORMATION AND COMMUNICATION ENGINEERING