Abstract: Methods and apparatus for digital signal processing of signals received from sensors are provided. A first input signal and a second input signal are received. A noise correlation statistic between the first input signal and the second input signal is estimated. An inter sensor signal model representative of a relationship between desired signal components present in the first input signal and the second input signal is estimated. Responsive to the noise correlation statistic meeting a predefined condition, estimating the inter sensor signal model is based on the noise correlation statistic. Responsive to the noise correlation statistic not meeting the predefined condition, estimating the inter sensor signal model is based on a constrained noise correlation statistic derived from the noise correlation statistic.

Abstract: Methods and apparatus for digital signal processing of signals received from sensors are provided. A first input signal and a second input signal are received. A noise correlation statistic between the first input signal and the second input signal is estimated. An inter sensor signal model representative of a relationship between desired signal components present in the first input signal and the second input signal is estimated. Responsive to the noise correlation statistic meeting a predefined condition, estimating the inter sensor signal model is based on the noise correlation statistic. Responsive to the noise correlation statistic not meeting the predefined condition, estimating the inter sensor signal model is based on a constrained noise correlation statistic derived from the noise correlation statistic.

Abstract: An audio signal is divided among exponentially related subband filters. The spectral flatness measure in each subband signal is determined and the measures are weighted and combined. The sum is compared with a threshold to determine the presence of music or noise. If music is detected, the noise estimation process in the noise reduction circuitry is turned off to avoid distorting the signal. If music is detected, residual echo suppression circuitry is also turned off to avoid inserting comfort noise.

Abstract: A background noise estimate based upon a modified Doblinger noise estimate is used for modulating the output of a pseudo-random phase spectrum generator to produce the comfort noise. The circuit for estimating noise includes a smoothing filter having a slower time constant for updating the noise estimate during noise than during speech. Comfort noise is smoothly inserted by basing the amount of comfort noise on the amount of noise suppression. A discrete inverse Fourier transform converts the comfort noise back to the time domain and overlapping windows eliminate artifacts that may have been produced during processing.

Abstract: In a noise suppresser, an input signal is converted to frequency domain by discrete Fourier analysis and divided into Bark bands. Noise is estimated for each band. The circuit for estimating noise includes a smoothing filter having a slower time constant for updating the noise estimate during noise than during speech. The noise suppresser further includes a circuit to adjust a noise suppression factor inversely proportional to the signal to noise ratio of each frame of the input signal. A noise estimate is subtracted from the signal in each band. A discrete inverse Fourier transform converts the signals back to the time domain and overlapping and combined windows eliminate artifacts that may have been produced during processing.