Multichannel post-filtering in nonstationary noise environments

In this paper, we present a multichannel post-filtering approach for minimizing the log-spectral amplitude distortion in nonstationary noise environments. The beamformer is realistically assumed to have a steering error, a blocking matrix that is unable to block all of the desired signal components, and a noise canceller that is adapted to the pseudo-stationary noise but not modified during transient interferences. A mild assumption is made that a desired signal component is stronger at the beamformer output than at any reference noise signal, and a noise component is strongest at one of the reference signals. The ratio between the transient power at the beamformer output and the transient power at the reference noise signals is used to indicate whether such a transient is desired or interfering. Based on a Gaussian statistical model and combined with an appropriate spectral enhancement technique, we derive estimators for the signal presence probability, the noise power spectral density, and the clean signal. The proposed method is tested in various nonstationary noise environments. Compared with single-channel post-filtering, a significantly reduced level of nonstationary noise is achieved without further distorting the desired signal components.

[1]  Michael S. Brandstein,et al.  Microphone Arrays - Signal Processing Techniques and Applications , 2001, Microphone Arrays.

[2]  R. Zelinski.  Noise reduction based on microphone array with LMS adaptive post-filtering , 1990 .

[3]  K. U. Simmer,et al.  Multi-microphone noise reduction techniques as front-end devices for speech recognition , 2000, Speech Commun..

[4]  Karl-Dirk Kammeyer,et al.  Broadband beamforming with adaptive postfiltering for speech acquisition in noisy environments , 1997, 1997 IEEE International Conference on Acoustics, Speech, and Signal Processing.

[5]  Israel Cohen,et al.  Speech enhancement for non-stationary noise environments , 2001, Signal Process..

[6]  Sven Fischer,et al.  Beamforming microphone arrays for speech acquisition in noisy environments , 1996, Speech Commun..

[7]  Ehud Weinstein,et al.  Signal enhancement using beamforming and nonstationarity with applications to speech , 2001, IEEE Trans. Signal Process..

[8]  Panos E. Papamichalis,et al.  Practical approaches to speech coding , 1987 .

[9]  C. Jim.  A comparison of two LMS constrained optimal array structures , 1977, Proceedings of the IEEE.

[10]  R. Zelinski,et al.  A microphone array with adaptive post-filtering for noise reduction in reverberant rooms , 1988, ICASSP-88., International Conference on Acoustics, Speech, and Signal Processing.

[11]  A. Wasiljeff,et al.  Adaptive Microphone Arrays for Noise Suppression in the Frequency Domain , 1992 .

[12]  P. Welch.  The use of fast Fourier transform for the estimation of power spectra: A method based on time averaging over short, modified periodograms , 1967 .

[13]  Iain McCowan,et al.  Robust speech recognition using near-field superdirective beamforming with post-filtering , 2000, 2000 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings (Cat. No.00CH37100).

[14]  Ephraim.  Speech enhancement using a minimum mean square error short-time spectral amplitude estimator , 1984 .

[15]  Israel Cohen,et al.  Microphone array post-filtering for non-stationary noise suppression , 2002, 2002 IEEE International Conference on Acoustics, Speech, and Signal Processing.

[16]  Sven Fischer,et al.  An Adaptive Microphone Array for Hands-Free Communication , 1995 .

[17]  Schuyler Quackenbush,et al.  Objective measures of speech quality , 1995 .

[18]  K. U. Simmer,et al.  MULTI-MICROPHONE NOISE REDUCTION BY POST-FILTER AND SUPERDIRECTIVE BEAMFORMER , 1999 .

[19]  John H. L. Hansen,et al.  Discrete-Time Processing of Speech Signals , 1993 .

[20]  Karl-Dirk Kammeyer,et al.  Multichannel noise reduction — Algorithms and theoretical limits , 1998, 9th European Signal Processing Conference (EUSIPCO 1998).

[21]  Andrzej Drygajlo,et al.  Combined Wiener and coherence filtering in wavelet domain for microphone array speech enhancement , 1998, Proceedings of the 1998 IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP '98 (Cat. No.98CH36181).

[22]  S. Nordholm,et al.  The broad-band Wiener solution for Griffiths-Jim beamformers , 1992, IEEE Trans. Signal Process..

[23]  L. J. Griffiths,et al.  An alternative approach to linearly constrained adaptive beamforming , 1982 .

[24]  Joerg Bitzer,et al.  Post-Filtering Techniques , 2001, Microphone Arrays.

[25]  Israel Cohen,et al.  Noise spectrum estimation in adverse environments: improved minima controlled recursive averaging , 2003, IEEE Trans. Speech Audio Process..

[26]  Rainer Martin,et al.  Noise power spectral density estimation based on optimal smoothing and minimum statistics , 2001, IEEE Trans. Speech Audio Process..

[27]  Régine Le Bouquin-Jeannès,et al.  Enhancement of speech degraded by coherent and incoherent noise using a cross-spectral estimator , 1997, IEEE Trans. Speech Audio Process..

[28]  Djamila Mahmoudi,et al.  A microphone array for speech enhancement using multiresolution wavelet transform , 1997, EUROSPEECH.

[29]  Yannick Mahieux,et al.  Analysis of noise reduction and dereverberation techniques based on microphone arrays with postfiltering , 1998, IEEE Trans. Speech Audio Process..

[30]  Karl-Dirk Kammeyer,et al.  Theoretical noise reduction limits of the generalized sidelobe canceller (GSC) for speech enhancement , 1999, 1999 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings. ICASSP99 (Cat. No.99CH36258).

[31]  Jörg Meyer,et al.  Multi-channel speech enhancement in a car environment using Wiener filtering and spectral subtraction , 1997, 1997 IEEE International Conference on Acoustics, Speech, and Signal Processing.

[32]  Eliathamby Ambikairajah,et al.  Speech enhancement for nonstationary noise environment , 2002, Asia-Pacific Conference on Circuits and Systems.

[33]  S. Thomas Alexander,et al.  Adaptive Signal Processing , 1986, Texts and Monographs in Computer Science.

[34]  Sven Fischer,et al.  Suppression of coherent and incoherent noise using a microphone array , 1994 .