Active noise reduction adaptive filter leakage adjusting
First Claim
Patent Images
1. A method for operating an active noise reduction system comprising:
- providing filter coefficients for an adaptive filter in response to a noise signal;
determining leakage factors;
smoothing the leakage factors to provide smoothed leakage factors;
applying the smoothed leakage factors to the filter coefficients to provide modified filter coefficients; and
applying the filter coefficients to an audio signal;
wherein the determining comprises determining a leakage factor as a function of the frequency of an input reference signal.
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Abstract
A method for determining leakage factors or adaptation rates, or both, for adaptive filters in an active noise reduction system. The leakage factor or adaptation rate, or both, may vary depending on a parameter of an input reference signal. The parameter may include one or more of reference signal input frequency, rate of change of reference input signal frequency, if a predetermined triggering condition exits, or if a predetermined event has occurred.
59 Citations
10 Claims
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1. A method for operating an active noise reduction system comprising:
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providing filter coefficients for an adaptive filter in response to a noise signal; determining leakage factors; smoothing the leakage factors to provide smoothed leakage factors; applying the smoothed leakage factors to the filter coefficients to provide modified filter coefficients; and applying the filter coefficients to an audio signal; wherein the determining comprises determining a leakage factor as a function of the frequency of an input reference signal. - View Dependent Claims (2)
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3. An active noise reduction system comprising:
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an adaptive filter, for providing an active noise reduction signal; a coefficient calculator, for providing filter coefficients for the adaptive filter; a leakage adjuster comprising a data smoother to provide smoothed leakage factors to apply to the filter coefficients, and further comprising circuitry to determine leakage factors as a function of the frequency of an input reference signal and to provide the leakage factors to the data smoother; and circuitry for applying the coefficients to an audio signal.
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4. A method for operating an active noise reduction system comprising:
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providing filter coefficients of an adaptive filter in response to a noise signal; determining leakage factors associated with the filter coefficients, wherein the determining comprises in response to a first triggering condition, providing a first leakage factor; in response to a second triggering condition, providing a second leakage factor, different from the first leakage factor; and in the absence of the first triggering condition and the second triggering condition, providing a default leakage factor; and applying the filter coefficients to an audio signal; wherein at least one of the providing the first leakage factor, providing the second leakage factor, and providing the default leakage factor comprises determining the leakage factor value as a function of the frequency of a reference input signal.
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5. A method comprising:
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determining a leakage factor for use in an adaptive filter of a noise reduction system as a function of the frequency of an input reference signal; applying the leakage factor to coefficients of the adaptive filter; and applying the coefficients to an audio signal. - View Dependent Claims (6, 7, 8, 9, 10)
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Specification