Research Of Microphone Array Speech Enhancement Method Based On Broadband Beamforming

By the bandwidth of the signal, Microphone array speech enhancement can be divided into two: Narrowband beamforming and broadband beamforming .However, in the actual speech communications environment, the speech is belongs broadband signal. According to the theory of array signal processing, assume that use the method of narrowband beamforming process the broadband speech signal, which will cause signal distortion, and the greater bandwidth of the signal, the more serious distortion.The broadband beamforming for speech enhancement is needed to improve the performance of array speech processing.As a new mathematical analysis, Wavelet analysis attracted widespread attention. Wavelet transform has the time - frequency analysis, multi-scale, multi-resolution feature, high or low frequency of the speech signal can be analyzed by different scales and frequencies,also can be achieved through the filter.A broadband beamforming method based on wavelet filterbanks and adaptive beamforming is proposed for speech enhancement in this paper. First, using the wavelet analysis filterbanks, noisy speech signals are transformed into wavelet domain with wavelet coefficients as output. Then the beamforming method of generalized sidelobe canceller (GSC) operates on the wavelet coefficients. Finally, the enhanced fullband speech signals were finally reconstructed by synthesizing the enhanced subband speech signals with the wavelet synthesis filterbanks, eliminated the noisy infection, and speech enhancement is realized.