Toward bias minimization in acoustic feedback cancellation systems.

A novel technique for bias suppression within acoustic feedback cancellation systems is proposed. This is achieved based on the use of all-pass filters in the forward part of the hearing aid. The poles of these filters are made time-varying, which results in a frequency response with constant magnitude and varying phase. This is a desired feature of the proposed approach, since the results from human psychoacoustics show that the human ear is not sensitive to moderate phase perturbations. The derivation of the proposed algorithms for the time variation of the location of the poles of all pass filters is based on a rigorous analysis of the phenomenon of bias in acoustic systems. Practical issues, such as the dependence of the steady-state error on the order of the all-pass filter, the number of varying poles, and their standard deviation are examined and strategies for the variation of the poles are introduced. Results obtained from a simulated hearing aid are provided to support the analysis. The quality of the processed audio signals is evaluated through subjective tests.

[1]  John Vanderkooy,et al.  On the Audibility of Midrange Phase Distortion in Audio Systems , 1980 .

[2]  D. K. Bustamante,et al.  Measurement and adaptive suppression of acoustic feedback in hearing aids , 1989, International Conference on Acoustics, Speech, and Signal Processing,.

[3]  James M. Kates,et al.  Feedback cancellation in hearing aids: results from a computer simulation , 1991, IEEE Trans. Signal Process..

[4]  August Kaelin,et al.  Feedback cancellation in hearing aids: results from using frequency-domain adaptive filters , 1994, Proceedings of IEEE International Symposium on Circuits and Systems - ISCAS '94.

[5]  Bill Gardner,et al.  HRTF Measurements of a KEMAR Dummy-Head Microphone , 1994 .

[6]  Patrick M. Zurek,et al.  Reducing acoustic feedback in hearing aids , 1995, IEEE Trans. Speech Audio Process..

[7]  W. G. Knecht.  Some notes on feedback suppression with adaptive filters in hearing aids , 1997, Proceedings of 1997 Workshop on Applications of Signal Processing to Audio and Acoustics.

[8]  Murtaza Ali,et al.  Stereophonic acoustic echo cancellation system using time-varying all-pass filtering for signal decorrelation , 1998, Proceedings of the 1998 IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP '98 (Cat. No.98CH36181).

[9]  T Lunner,et al.  System identification of feedback in hearing aids. , 1999, The Journal of the Acoustical Society of America.

[10]  Abeer Alwan,et al.  Steady-state analysis of continuous adaptation in acoustic feedback reduction systems for hearing-aids , 2000, IEEE Trans. Speech Audio Process..

[11]  Boaz Rafaely,et al.  Control of feedback in hearing aids-a robust filter design approach , 2000, IEEE Trans. Speech Audio Process..

[12]  Urban Forssell,et al.  Bias of feedback cancellation algorithms based on direct closed loop identification , 2000, 2000 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings (Cat. No.00CH37100).

[13]  P M Zurek,et al.  Evaluation of feedback-reduction algorithms for hearing aids. , 2000, The Journal of the Acoustical Society of America.

[14]  Urban Forssell,et al.  Bias of feedback cancellation algorithms in hearing aids based on direct closed loop identification , 2001, IEEE Trans. Speech Audio Process..

[16]  Boaz Rafaely,et al.  Robust compensation with adaptive feedback cancellation in hearing aids , 2003, Speech Commun..

[17]  F. Fontana,et al.  A digital bandpass/bandstop complementary equalization filter with independent tuning characteristics , 2003, IEEE Signal Processing Letters.

[18]  Danilo P. Mandic,et al.  Bias reduction in acoustic feedback cancellation systems with varying all-pass filters , 2006 .