Background noise reduction system
First Claim
Patent Images
1. A method for reducing background noise in an audio signal, comprising:
- converting sound into an analog signal;
digitizing the analog signal to obtain a discrete output signal;
detecting structure-borne noise by an acoustic emission sensor to obtain an acoustic noise reference signal;
digitizing the acoustic noise reference signal to obtain a discrete acoustic noise reference signal; and
detecting noise to obtain a reference noise signal;
digitizing the reference noise signal to obtain a discrete reference noise signal;
calculating a correlation between the discrete output signal and the discrete acoustic noise reference signal to obtain a first correlation value;
calculating a correlation between the discrete output signal and the discrete reference noise signal to obtain a second correlation value;
adaptively filtering the discrete acoustic noise reference signal to obtain a noise estimate signal, if the first correlation value is greater than the second correlation value;
adaptively filtering the discrete reference noise signal to obtain the noise estimate signal, if the first correlation value is not greater than the second correlation value; and
subtracting the noise estimate signal from the discrete output signal to obtain a noise compensated digital audio signal.
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Abstract
A noise reduction system includes a microphone configured to detect an acoustic signal. A first digitizer converts an output of the microphone into a discrete output signal. An acoustic sensor detects structure-borne noise, and a second digitizer converts an output of the acoustic sensor into a discrete acoustic noise reference signal. A noise compensation circuit processes the discrete output signal based on the discrete acoustic noise reference signal.
12 Citations
20 Claims
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1. A method for reducing background noise in an audio signal, comprising:
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converting sound into an analog signal; digitizing the analog signal to obtain a discrete output signal; detecting structure-borne noise by an acoustic emission sensor to obtain an acoustic noise reference signal; digitizing the acoustic noise reference signal to obtain a discrete acoustic noise reference signal; and detecting noise to obtain a reference noise signal; digitizing the reference noise signal to obtain a discrete reference noise signal; calculating a correlation between the discrete output signal and the discrete acoustic noise reference signal to obtain a first correlation value; calculating a correlation between the discrete output signal and the discrete reference noise signal to obtain a second correlation value; adaptively filtering the discrete acoustic noise reference signal to obtain a noise estimate signal, if the first correlation value is greater than the second correlation value; adaptively filtering the discrete reference noise signal to obtain the noise estimate signal, if the first correlation value is not greater than the second correlation value; and subtracting the noise estimate signal from the discrete output signal to obtain a noise compensated digital audio signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A non-transitory computer-readable storage medium having processor executable instructions to reduce background noise in an audio signal, by performing the acts of:
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detecting an acoustic signal by converting sound into digital data; detecting structure-borne noise by an acoustic emission sensor to obtain an acoustic noise reference signal; digitizing the acoustic noise reference signal to obtain a discrete acoustic noise reference signal; and detecting noise by a reference microphone to obtain a reference noise signal; digitizing the reference noise signal to obtain a discrete reference noise signal; calculating a correlation between the digital data and the discrete acoustic noise reference signal to obtain a first correlation value; calculating a correlation between the digital data and the discrete reference noise signal to obtain a second correlation value; and adaptively filtering the discrete acoustic noise reference signal to obtain a noise estimate signal, if the first correlation value is greater than the second correlation value; adaptively filtering the discrete reference noise signal to obtain the noise estimate signal if the first correlation value is not greater than the second correlation value; and subtracting the noise estimate signal from the digital data to obtain a noise compensated digital audio signal. - View Dependent Claims (11)
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12. A noise reduction system comprising:
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a microphone configured to detect an acoustic signal; a first digitizer configured to convert an output of the microphone and provide a digitized microphone output signal; an acoustic sensor configured to detect structure-borne noise; a second digitizer configured to convert an output of the acoustic sensor and provide a digitized acoustic noise reference signal; and a reference microphone configured to detect noise; a digitizer configured to digitize an output of the reference microphone and provide a digitized reference microphone noise signal; a first correlation circuit configured to calculate a correlation between the digitized microphone output signal and the digitized acoustic noise reference signal to obtain a first correlation value; a second correlation circuit configured to calculate a correlation between the digitized microphone output signal and the digitized reference microphone noise signal to obtain a second correlation value; a signal processor configured to adaptively filter the digitized acoustic noise reference signal to obtain a noise estimate signal, if the first correlation value is greater than the second correlation value; the signal processor configured to adaptively filter the digitized reference microphone noise signal to obtain the noise estimate signal, if the first correlation value is not greater than the second correlation value; and a subtraction circuit configured to subtract the noise estimate signal from the digitized microphone output signal to produce a noise compensated digital audio signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification