Systems and methods for hybrid adaptive noise cancellation
First Claim
1. A personal audio device comprising:
- a personal audio device housing;
a transducer coupled to 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 coupled to the housing for providing a reference microphone signal indicative of the ambient audio sounds;
an error microphone coupled to 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;
a feedforward filter having a response that generates a feedforward anti-noise signal component from the reference microphone signal;
a feedback adaptive filter having a response that generates a feedback anti-noise signal component from a synthesized reference feedback, the synthesized reference feedback based on a difference between the error microphone signal and the feedback anti-noise signal component, and wherein the anti-noise signal comprises the feedforward anti-noise signal component and the feedback anti-noise signal component; and
a feedback coefficient control block that shapes the response of the feedback adaptive filter in conformity with a correlation between the error microphone signal and the synthesized reference feedback by adapting the response of the feedback adaptive filter to minimize the ambient audio sounds in the error microphone signal.
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Accused Products
Abstract
In accordance with systems and methods of this disclosure, a method may include generating a feedforward anti-noise signal component from a result of measuring with the reference microphone countering the effects of ambient audio sounds at an acoustic output of a transducer by filtering an output of the reference microphone, adaptively generating a feedback anti-noise signal component from a result of measuring with an error microphone for countering the effects of ambient audio sounds at the acoustic output of the transducer by adapting a response of a feedback adaptive filter that filters a synthesized reference feedback to minimize the ambient audio sounds in the error microphone signal, wherein the synthesized reference feedback is based on a difference between the error microphone signal and the feedback anti-noise signal component.
289 Citations
15 Claims
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1. A personal audio device comprising:
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a personal audio device housing; a transducer coupled to 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 coupled to the housing for providing a reference microphone signal indicative of the ambient audio sounds; an error microphone coupled to 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; a feedforward filter having a response that generates a feedforward anti-noise signal component from the reference microphone signal; a feedback adaptive filter having a response that generates a feedback anti-noise signal component from a synthesized reference feedback, the synthesized reference feedback based on a difference between the error microphone signal and the feedback anti-noise signal component, and wherein the anti-noise signal comprises the feedforward anti-noise signal component and the feedback anti-noise signal component; and a feedback coefficient control block that shapes the response of the feedback adaptive filter in conformity with a correlation between the error microphone signal and the synthesized reference feedback by adapting the response of the feedback adaptive filter to minimize the ambient audio sounds in the error microphone signal. - View Dependent Claims (2, 3, 4, 5)
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6. A method for canceling ambient audio sounds in the proximity of a transducer of a personal audio device, the method comprising:
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receiving a reference microphone signal indicative of ambient audio sounds; receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer; generating a feedforward anti-noise signal component from the reference microphone signal countering the effects of ambient audio sounds at an acoustic output of the transducer by filtering an output of the reference microphone; adaptively generating a feedback anti-noise signal component for countering the effects of ambient audio sounds at the acoustic output of the transducer by adapting, in conformity with a correlation between the error microphone signal and a synthesized reference feedback, a response of a feedback adaptive filter that filters the synthesized reference feedback to minimize the ambient audio sounds in the error microphone signal, wherein the synthesized reference feedback is based on a difference between the error microphone signal and the feedback anti-noise signal component; and combining the anti-noise signal with a source audio signal to generate an audio signal provided to the transducer. - View Dependent Claims (7, 8, 9, 10)
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11. 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 effect 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; a feedforward filter having a response that generates a feedforward anti-noise signal component from the reference microphone signal; a feedback adaptive filter having a response that generates a feedback anti-noise signal component from a synthesized reference feedback, the synthesized reference feedback based on a difference between the error microphone signal and the feedback anti-noise signal component, and wherein the anti-noise signal comprises the feedforward anti-noise signal component and the feedback anti-noise signal component; and a feedback coefficient control block that shapes the response of the feedback adaptive filter in conformity with a correlation between the error microphone signal and the synthesized reference feedback by adapting the response of the feedback adaptive filter to minimize the ambient audio sounds in the error microphone signal. - View Dependent Claims (12, 13, 14, 15)
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Specification