Telephonic communications – Substation or terminal circuitry – Noise suppression
Reexamination Certificate
2004-04-23
2009-02-17
Jamal, Alexander (Department: 2614)
Telephonic communications
Substation or terminal circuitry
Noise suppression
Reexamination Certificate
active
07492889
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.
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Acoustic Technologies Inc.
Jamal Alexander
Wille Paul F.
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