BANDLIMITING ANTI-NOISE IN PERSONAL AUDIO DEVICES HAVING ADAPTIVE NOISE CANCELLATION (ANC)
First Claim
1. A personal audio device, comprising:
- a personal audio device housing;
a transducer mounted on the housing for reproducing an audio signal including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer;
a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds;
an error microphone mounted on the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer; and
a processing circuit that implements an adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit shapes the response of the adaptive filter in conformity with the error microphone signal and the reference microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds at the error microphone, wherein at least one of the error microphone signal or the reference microphone signal are filtered to weight one or more first particular frequency regions so that the response of the adaptive filter is biased to alter a degree of the minimization of the ambient audio sounds in the first particular frequency regions.
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Accused Products
Abstract
A personal audio device, such as a wireless telephone, includes noise canceling that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is provided proximate the speaker to measure the output of the transducer in order to control the adaptation of the anti-noise signal and to estimate an electro-acoustical path from the noise canceling circuit through the transducer. The anti-noise signal is adaptively generated to minimize the ambient audio sounds at the error microphone. A processing circuit that performs the adaptive noise canceling (ANC) function also filters one or both of the reference and/or error microphone signals, to bias the adaptation of the adaptive filter in one or more frequency regions to alter a degree of the minimization of the ambient audio sounds at the error microphone.
76 Citations
20 Claims
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1. A personal audio device, comprising:
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a personal audio device housing; a transducer mounted on the housing for reproducing an audio signal including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds; an error microphone mounted on the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements an adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit shapes the response of the adaptive filter in conformity with the error microphone signal and the reference microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds at the error microphone, wherein at least one of the error microphone signal or the reference microphone signal are filtered to weight one or more first particular frequency regions so that the response of the adaptive filter is biased to alter a degree of the minimization of the ambient audio sounds in the first particular frequency regions. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of canceling ambient audio sounds in the proximity of a transducer of a personal audio device, the method comprising:
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first measuring ambient audio sounds with a reference microphone to produce a reference microphone signal; second measuring an output of the transducer and the ambient audio sounds at the transducer with an error microphone; adaptively generating an anti-noise signal from a result of the first measuring and the second measuring to minimize the effects of ambient audio sounds at the error microphone by adapting a response of an adaptive filter that filters an output of the reference microphone; combining the anti-noise signal with a source audio signal to generate an audio signal provided to the transducer; and filtering at least one of the error microphone signal or the reference microphone signal to weight one or more first particular frequency regions so that the response of the adaptive filter is biased to alter a degree of the minimization of the ambient audio sounds in the first particular frequency regions. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An integrated circuit for implementing at least a portion of a personal audio device, comprising:
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an output for providing a signal to a transducer including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; a reference microphone input for receiving a reference microphone signal indicative of the ambient audio sounds; an error microphone input for receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements an adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit shapes the response of the adaptive filter in conformity with the error microphone signal and the reference microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds in the error microphone signal, wherein at least one of the error microphone signal or the reference microphone signal are filtered to weight one or more first particular frequency regions so that the response of the adaptive filter is biased to alter a degree of the minimization of the ambient audio sounds in the first particular frequency regions. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification