Analysis/synthesis-based microphone array speech enhancer with variable signal distortion
First Claim
1. Apparatus which relates to a microphone array speech enhancement algorithm based on analysis/synthesis filtering that allows for variable signal distortion, which is used to suppress additive noise and interference;
- wherein the apparatus comprises a microphone array of K sensors, processing structure means for delaying received signals so that desired signal components add coherently, means for filtering each delayed signal through an analysis filter bank to generate a plurality of channel signals, means for summing corresponding channel signals from said sensors, means for applying a signal degrading and noise suppressing independent weighting gain to each said channel signal, and means for combining gain-weighted channel signals using a synthesis filter.
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Abstract
A microphone array speech enhancement algorithm based on analysis/synthesis filtering that allows for variable signal distortion. The algorithm is used to suppress additive noise and interference. The processing structure consists of delaying the received signals so that the desired signal components add coherently, filtering each of the delayed signals through an analysis filter bank, summing the corresponding channel outputs from the sensors, applying a gain function to the channel outputs, and combining the weighted channel outputs using a synthesis filter. The structure uses two different gain functions, both of which are based on cross correlations of the channel signals from the two sensors. The first gain yields the GEQ-I array, which performs best for the case of a desired speech signal corrupted by uncorrelated white background noise. The second gain yields the GEQ-II array, which performs best for the case where there are more signals than microphones. The GEQ-II gain allows for a trade-off on a channel-dependent basis of additional signal degradation in exchange for additional noise and interference suppression.
301 Citations
8 Claims
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1. Apparatus which relates to a microphone array speech enhancement algorithm based on analysis/synthesis filtering that allows for variable signal distortion, which is used to suppress additive noise and interference;
- wherein the apparatus comprises a microphone array of K sensors, processing structure means for delaying received signals so that desired signal components add coherently, means for filtering each delayed signal through an analysis filter bank to generate a plurality of channel signals, means for summing corresponding channel signals from said sensors, means for applying a signal degrading and noise suppressing independent weighting gain to each said channel signal, and means for combining gain-weighted channel signals using a synthesis filter.
- View Dependent Claims (2, 3)
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4. Microphone-array apparatus comprising:
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A. a plurality of microphone elements for converting acoustic signals into electrical microphone output signals; B. analysis filtering means connected with said microphone output signals for generating a plurality of channel signals for each of said microphone output signals, each microphone output signal connecting with an identical different analysis filtering element and each said different analysis filtering element having corresponding output channels of like frequency characteristics; C. channel summing means, including an identical different channel summing element connected with each said analysis filtering element output channel of like frequency characteristics, to generate a plurality of like-channel sum signals; D. weighting means, including a plurality of weighting elements each connected to one of said like-channel sum signals, for generating weighted like-channel sum signals and for trading additional degradation of a selected signal component in each said like-channel sum signal for additional suppression of noise and interference components present in said like-channel sum signal, each said like-channel sum signal trade being independent of each other such trade; E. synthesis filtering means for filtering and combining said weighted like-channel sum signals into an output signal. - View Dependent Claims (5, 6, 7)
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8. Additive noise and interference-suppressing microphone array speech enhancement apparatus comprising the combination of:
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a K element array of microphones each connected to an input signal path; an array of signal delaying elements, each of coherent signal-addition-enabling delay interval, located in said input signal paths; an array of similar analysis filters located one in each of said input signal paths, each said analysis filter having a plurality of selected frequency components-inclusive signal output channels; a signal summing element connected to a corresponding signal output channel of each said analysis filter; an array of weighting function elements each connected to an output port of a signal summing element; each of said weighting function elements including an independently determined and signal cross correlation-controlled gain selection element; each of said gain selection elements having an increased signal distortion with increased noise suppression characteristic; an output signal generating synthesis filter element connected with an output signal port of each said weighting function element.
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Specification