Design and analysis of a BLPC vocoder-based adaptive feedback cancellation with probe noise

Ankita Anand, Asutosh Kar, M.N.S. Swamy

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

9 Citationer (Scopus)

Abstract

The band-limited linear predictive coding (BLPC) vocoder-based adaptive feedback cancellation (AFC)
removes the high-frequency bias, while the low frequency bias persists between the desired input signal
and the loudspeaker signal in the estimate of the feedback path. In this paper, we present a BLPC vocoderbased
adaptive feedback canceller with probe noise with an objective of reducing the low-frequency bias
in digital hearing-aids. A step-wise mathematical analysis of the proposed feedback canceller is presented
employing the recursive least square and normalized least mean square adaptive algorithms. It
is observed that the optimal solution of the feedback path is unbiased for an unshaped probe noise,
but is biased for a shaped probe signal; the bias term does not consist of correlation between the desired
input and the loudspeaker output. The identifiability conditions are analysed and it is shown that a delay,
greater than or equal to the length of the adaptive filter, must be introduced in the forward path to
achieve an unbiased feedback path estimate. Algorithm analysis and computer simulations presented
in this paper justify the reason for selecting the proposed design over the existing BLPC vocoder-based
feedback cancellation algorithm.
OriginalsprogEngelsk
TidsskriftApplied Acoustics
Vol/bind115
Sider (fra-til)196-208
ISSN0003-682X
DOI
StatusUdgivet - 1 jan. 2017

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