NOISE ESTIMATION FOR USE WITH NOISE REDUCTION AND ECHO CANCELLATION IN PERSONAL COMMUNICATION
First Claim
1. A method for audio signal processing, the method comprising:
- in one or more frequency subbands, receiving M communication signals in time frames and comprising a target signal and a noise signal, where M≧
2;
in each subband, processing the M subband communication signals with a set of beamformer coefficients to obtain a beamformer output signal;
in each subband, processing the M subband communication signals in N linearly independent target-cancelling beamformers, where 1≦
N<
M, to obtain N target-cancelled signals wherein the target signal is suppressed relative to the noise signal;
processing the communication signals with a target absence detector to obtain a target absence signal;
in each subband, estimating a covariance matrix of order N of the target-cancelled signals as an average, where individual time frames are weighted as a function of the target absence signal;
in each subband, estimating an inverse target-cancelled covariance matrix of order N;
in each subband, determining a real-valued scaling factor in dependence of the inverse target-cancelled covariance matrix and the N target-cancelled signals;
in each subband, determining an initial estimate of the noise power in the beamformer output signal as an average, where individual time frames are weighted using said function of the target absence signal;
in each subband, multiplying the initial noise estimate with the scaling factor to obtain a refined estimate of the noise power in the beamformer output signal.
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Abstract
A method comprises processing M subband communication signals and N target-cancelled signals in each subband with a set of beamformer coefficients to obtain an inverse target-cancelled covariance matrix of order N in each band; using a target absence signal to obtain an initial estimate of the noise power in a beamformer output signal averaged over recent frames with target absence in each subband; multiplying the initial noise estimate with a noise correction factor to obtain a refined estimate of the power of the beamformer output noise signal component in each subband; processing the refined estimate with the magnitude of the beamformer output to obtain a postfilter gain value in each subband; processing the beamformer output signal with the postfilter gain value to obtain a postfilter output signal in each subband; and processing the postfilter output subband signals to obtain an enhanced beamformed output signal.
112 Citations
20 Claims
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1. A method for audio signal processing, the method comprising:
-
in one or more frequency subbands, receiving M communication signals in time frames and comprising a target signal and a noise signal, where M≧
2;in each subband, processing the M subband communication signals with a set of beamformer coefficients to obtain a beamformer output signal; in each subband, processing the M subband communication signals in N linearly independent target-cancelling beamformers, where 1≦
N<
M, to obtain N target-cancelled signals wherein the target signal is suppressed relative to the noise signal;processing the communication signals with a target absence detector to obtain a target absence signal; in each subband, estimating a covariance matrix of order N of the target-cancelled signals as an average, where individual time frames are weighted as a function of the target absence signal; in each subband, estimating an inverse target-cancelled covariance matrix of order N; in each subband, determining a real-valued scaling factor in dependence of the inverse target-cancelled covariance matrix and the N target-cancelled signals; in each subband, determining an initial estimate of the noise power in the beamformer output signal as an average, where individual time frames are weighted using said function of the target absence signal; in each subband, multiplying the initial noise estimate with the scaling factor to obtain a refined estimate of the noise power in the beamformer output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification