Subband Adaptive Feedback Control in Hearing Aids with Increased User Comfort

Document type: Researchreports
Full text:
Author(s): Nils Westerlund, Nedelko Grbic, Mattias Dahl
Title: Subband Adaptive Feedback Control in Hearing Aids with Increased User Comfort
Series: Research Report
Year: 2006
Issue: 1
ISSN: 1103-1581
Organization: Blekinge Institute of Technology
Department: School of Engineering - Dept. of Signal Processing (Sektionen för teknik – avd. för signalbehandling)
School of Engineering S- 372 25 Ronneby
+46 455 38 50 00
Authors e-mail:
Language: English
Abstract: This report describes important physiological and anatomical aspects of human hearing, including instruments for hearing improvements, i.e. hearing aids. One common problem with hearing aids is acoustic feedback (howling). A new subband Adaptive Feedback Control (AFC) system for hearing aids is proposed. This system detects howling by calculating distances between zero crossings in the subband input signal. A stable subband zero crossing distance measure indicates that howling is present in a particular subband. This triggers an adaptation to estimate and attenuate the feedback channel. The adaptation is driven by a probe noise sequence constrained in both time and frequency. This constraint implies increased signal quality and that user discomfort due to emitted probe noise is reduced. Also, an effective and reliable adaptation is achieved. The method has proven to operate well in computer simulations, with speech as well as music as signal input. Initial simulations indicate that an increased hearing aid gain of at least 15 dB is possible.
Subject: Signal Processing\Speech Enhancement
Keywords: Speech Enhancement, Adaptive Feedback Control, Hearing Aids, Zero Crossing
URN: urn:nbn:se:bth-00314