Ear-coupling detection and adjustment of adaptive response in noise-canceling in personal audio devices
First Claim
1. A method of canceling ambient audio sounds in the proximity of a transducer of a personal audio device, the method comprising:
- first measuring ambient audio sounds with a reference microphone to provide a reference microphone signal;
second measuring an output of the transducer with an error microphone to provide an error microphone signal;
adaptively generating an anti-noise signal from the reference microphone signal for countering the effects of ambient audio sounds at an acoustic output of the transducer 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;
shaping the source audio using a secondary path adaptive filter having a secondary path estimated response to generate shaped source audio;
removing the shaped source audio from the error microphone signal to provide an error signal indicative of the combined anti-noise and ambient audio sounds delivered to the listener, wherein the adaptively generating adapts the response of the adaptive filter to minimize the error signal;
determining a degree of coupling between the transducer and an ear of the listener from values of coefficients of the secondary path adaptive filter and detecting changes in the degree of coupling;
altering the response of the adaptive filter in conformity with detecting the changes in the degree of coupling between the transducer and the ear of the listener;
combining the anti-noise signal with a source audio signal; and
providing a result of the combining to the transducer to generate the acoustic output.
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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 the speaker to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit determines a degree of coupling between the user'"'"'s ear and the transducer and adjusts the adaptive cancellation of the ambient sounds to prevent erroneous and possibly disruptive generation of the anti-noise signal if the degree of coupling lies either below or above a range of normal operating ear contact pressure.
302 Citations
18 Claims
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1. 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 provide a reference microphone signal; second measuring an output of the transducer with an error microphone to provide an error microphone signal; adaptively generating an anti-noise signal from the reference microphone signal for countering the effects of ambient audio sounds at an acoustic output of the transducer 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; shaping the source audio using a secondary path adaptive filter having a secondary path estimated response to generate shaped source audio; removing the shaped source audio from the error microphone signal to provide an error signal indicative of the combined anti-noise and ambient audio sounds delivered to the listener, wherein the adaptively generating adapts the response of the adaptive filter to minimize the error signal; determining a degree of coupling between the transducer and an ear of the listener from values of coefficients of the secondary path adaptive filter and detecting changes in the degree of coupling; altering the response of the adaptive filter in conformity with detecting the changes in the degree of coupling between the transducer and the ear of the listener; combining the anti-noise signal with a source audio signal; and providing a result of the combining to the transducer to generate the acoustic output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. 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 a processing circuit that implements an adaptive filter having a response that shapes the anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener and a secondary path adaptive filter for shaping the source audio, wherein the secondary path adaptive filter has a secondary path estimated response to generate shaped source audio, wherein the processing circuit removes the shaped source audio from the error microphone signal to generate an error signal indicative of the combined anti-noise and ambient audio sounds delivered to the listener, wherein the processing circuit determines a degree of coupling between the transducer and an ear of the listener from values of coefficients of the secondary path adaptive filter that determines the secondary path estimate response and detects changes in the degree of coupling, and wherein the processing circuit alters the response of the adaptive filter in conformity with the processing circuit having detected changes in the degree of coupling between the transducer and the ear of the listener. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification