Acoustic feedback cancellation for a multi-microphone earpiece based on a null-steering beamformer
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In order to reduce acoustic feedback in hearing aids, adaptive filters are commonly used to estimate the feedback contribution in the microphone(s). While theoretically allowing for perfect feedback cancellation, in practice the solution is typically biased due to the closed-loop acoustical system. In this paper, we propose to use a fixed beamformer to cancel the acoustic feedback for an earpiece with multiple integrated microphones and loudspeakers. By steering a spatial null in the direction of the hearing aid loudspeaker we show that theoretically perfect feedback cancellation can be achieved. Experimental results using measured acoustic feedback paths from an earpiece with two microphones in the vent and a third microphone in the concha show that the proposed fixed beamformer provides a reduction of the acoustic feedback and substantially increases the added stable gain while maintaining a high perceptual speech quality even for unknown acoustic feedback paths, e.g., after repositioning of the earpiece or with a telephone receiver close to the ear.
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Nakagawa, C.; Nordholm, S.; Yan, Wei-Yong (2015)Acoustic feedback cancellation in hearing aids makes use of adaptive filters to continuously identify and track variations to the feedback path. One of the biggest problems remaining in using adaptive filters for feedback ...
Null-steering beamformer for acoustic feedback cancellation in a multi-microphone earpiece optimizing the maximum stable gainSchepker, H.; Tran, L.; Nordholm, Sven; Doclo, S. (2017)© 2017 IEEE. Commonly adaptive filters are used to reduce the acoustic feedback in hearing aids. While theoretically allowing for perfect cancellation of the feedback signal, in practice the adaptive filter solution is ...
Evaluation of two-microphone acoustic feedback cancellation using uniform and non-uniform sub-bands in hearing AIDSTran, Linh T.T.; Dam, Hai Huyen Heidi; Schepker, H.; Doclo, S.; Nordholm, Sven (2016)The limiting feature of hearing aids is acoustic feedback. This feedback problem has been approached by using an acoustic feedback canceller. This well known identification in a loop problem, will give a biased solution ...