Active noise reduction adaptive filter leakage adjusting
First Claim
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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; and
applying the smoothed leakage factors to the filter coefficients to provide modified filter coefficients;
wherein the determining provides a leakage factor with one of a plurality of values as a function of the magnitude of a cancellation signal that is output by the adaptive filter.
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Abstract
An active noise reduction system using adaptive filters. A method of operation the active noise reduction system includes smoothing a stream of leakage factors. The frequency of a noise reduction signal may be related to the engine speed of an engine associated with the system within which the active noise reduction system is operated. The engine speed signal may be a high latency signal and may be obtained by the active noise reduction system over audio entertainment circuitry.
50 Citations
24 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; and applying the smoothed leakage factors to the filter coefficients to provide modified filter coefficients; wherein the determining provides a leakage factor with one of a plurality of values as a function of the magnitude of a cancellation signal that is output by the adaptive filter. - View Dependent Claims (2, 12, 13)
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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; and a leakage adjuster comprising a data smoother to provide smoothed leakage factors to apply to the filter coefficients, the leakage adjuster comprising circuitry to provide leakage factors having one of a plurality of values as a function of the magnitude of the output of the active noise reduction signal and to provide the leakage factors to the data smoother. - View Dependent Claims (4, 14, 15)
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5. 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 wherein at least one of the providing the first leakage factor and providing the second leakage factor comprises providing a leakage factor value calculated as one of a plurality of continuous functions of the magnitude of a cancellation signal that is output by the active noise reduction system.
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6. A method comprising:
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determining a leakage factor for use in an adaptive filter of a noise reduction system in a manner that the leakage factor can have one of a plurality of values as a function of the magnitude of the output of the adaptive filter; applying the leakage factor to coefficients of the adaptive filter; and applying the coefficients to an audio signal. - View Dependent Claims (7, 8, 9, 10, 11, 16, 17)
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18. 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; calculating leakage factors according to one of a plurality of mathematical relationships between the leakage factor and an operating condition of the active noise reduction system; smoothing the leakage factors to provide smoothed leakage factors; and applying the smoothed leakage factors to the filter coefficients to provide modified filter coefficients. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification