SEQUENCED ADAPTATION OF ANTI-NOISE GENERATOR RESPONSE AND SECONDARY PATH RESPONSE IN AN ADAPTIVE NOISE CANCELING SYSTEM
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 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 adaptively generates the anti-noise signal from the reference signal by adapting a first adaptive filter to reduce the presence of the ambient audio sounds heard by the listener in conformity with an error signal and the reference microphone signal, wherein the processing circuit implements a secondary path adaptive filter having a secondary path response that shapes the source audio and a combiner that removes the source audio from the error microphone signal to provide the error signal, and wherein the processing circuit sequences adaptation of the secondary path adaptive filter and the first adaptive filter so that adaptation of a first one of the first adaptive filter or the secondary path adaptive filter is initiated only after adaptation of another one of the first adaptive filter or the secondary path adaptive filter is substantially completed or halted.
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Accused Products
Abstract
A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit 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 also provided proximate to the speaker to provide an error signal indicative of the effectiveness of the noise cancellation. A secondary path estimating adaptive filter is used to estimate the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. Adaptation of adaptive filters is sequenced so that update of their coefficients does not cause instability or error in the update. A level of the source audio with respect to the ambient audio can be determined to determine whether the system may generate erroneous anti-noise and/or become unstable.
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Citations
42 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 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 adaptively generates the anti-noise signal from the reference signal by adapting a first adaptive filter to reduce the presence of the ambient audio sounds heard by the listener in conformity with an error signal and the reference microphone signal, wherein the processing circuit implements a secondary path adaptive filter having a secondary path response that shapes the source audio and a combiner that removes the source audio from the error microphone signal to provide the error signal, and wherein the processing circuit sequences adaptation of the secondary path adaptive filter and the first adaptive filter so that adaptation of a first one of the first adaptive filter or the secondary path adaptive filter is initiated only after adaptation of another one of the first adaptive filter or the secondary path adaptive filter is substantially completed or halted. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of countering effects of ambient audio sounds by a personal audio device, the method comprising:
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adaptively generating the anti-noise signal from the reference signal by adapting a first adaptive filter to reduce the presence of ambient audio sounds heard by the listener in conformity with an error signal and the reference microphone signal; combining the anti-noise signal with source audio; providing a result of the combining to a transducer; measuring the ambient audio sounds with a reference microphone; measuring an acoustic output of the transducer and the ambient audio sounds with an error microphone; implementing a secondary path adaptive filter having a secondary path response that shapes the source audio and a combiner that removes the source audio from the error microphone signal to provide the error signal; and sequencing adaptation of the secondary path adaptive filter and the first adaptive filter so that adaptation of a first one of the first adaptive filter or the secondary path adaptive filter is initiated only after adaptation of another one of the first adaptive filter or the secondary path adaptive filter is substantially completed or halted. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An integrated circuit for implementing at least a portion of a personal audio device, comprising:
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an output for providing an output signal to an output 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 acoustic output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that adaptively generates the anti-noise signal from the reference signal by adapting a first adaptive filter to reduce the presence of the ambient audio sounds heard by the listener in conformity with an error signal and the reference microphone signal, wherein the processing circuit implements a secondary path adaptive filter having a secondary path response that shapes the source audio and a combiner that removes the source audio from the error microphone signal to provide the error signal, and wherein the processing circuit sequences adaptation of the secondary path adaptive filter and the first adaptive filter so that adaptation of a first one of the first adaptive filter or the secondary path adaptive filter is initiated only after adaptation of another one of the first adaptive filter or the secondary path adaptive filter is substantially completed or halted. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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25. 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 an anti-noise signal for countering effects of ambient audio sounds in an acoustic output of the output transducer; a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds; and a processing circuit within the housing that adaptively generates the anti-noise signal from the reference microphone signal such that the anti-noise signal causes substantial cancellation of the ambient audio sounds, wherein the processing circuit, in response to determining that an amplitude of acoustic leakage of the source audio into the reference microphone is substantial with respect to an amplitude of the ambient audio sounds, takes action to prevent improper generation of the anti-noise signal. - View Dependent Claims (26, 27, 28, 29, 30)
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31. A method of countering effects of ambient audio sounds by a personal audio device, the method comprising:
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adaptively generating an anti-noise signal from the reference microphone signal with a first adaptive filter such that the anti-noise signal causes substantial cancellation of the ambient audio sounds; combining the anti-noise signal with source audio; providing a result of the combining to a transducer; measuring the ambient audio sounds with a reference microphone; determining whether an amplitude of acoustic leakage of the source audio into the reference microphone is substantial with respect to an amplitude of the ambient audio sounds; and responsive to determining that the amplitude of the acoustic leakage of the source audio into the reference microphone is substantial with respect to the amplitude of the ambient audio sounds, taking action to prevent improper generation of the anti-noise signal. - View Dependent Claims (32, 33, 34, 35, 36)
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37. An integrated circuit for implementing at least a portion of a personal audio device, comprising:
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an output for providing an output signal to an output 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; and a processing circuit within the housing that adaptively generates the anti-noise signal from the reference microphone signal such that the anti-noise signal causes substantial cancellation of the ambient audio sounds, wherein the processing circuit, in response to determining that an amplitude of acoustic leakage of the source audio into the reference microphone is substantial with respect to an amplitude of the ambient audio sounds, takes action to prevent improper generation of the anti-noise signal. - View Dependent Claims (38, 39, 40, 41, 42)
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Specification