Noise burst adaptation of secondary path adaptive response in noise-canceling personal audio devices
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 a first anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer;
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 ambient audio sounds at the transducer;
a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds;
a noise source for providing a noise signal; and
a processing circuit that implements a first adaptive filter that generates a second anti-noise signal from the reference microphone signal, a secondary path adaptive filter having a secondary path response that shapes the source audio and a combiner that removes resulting shaped source audio from the error microphone signal to provide an error signal, wherein the processing circuit filters the error signal with a predetermined response to generate a filtered error signal and combines the second anti-noise signal with the filtered error signal to yield the first anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener in conformity with the error signal and the reference microphone signal, and wherein the processing circuit injects intermittent bursts of noise from the noise source into the secondary path adaptive filter and the audio signal reproduced by the transducer and permits the secondary path adaptive filter to adapt during the intermittent bursts of noise.
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Accused Products
Abstract
A personal audio device, such as a wireless telephone, generates an anti-noise signal from an error microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. The error microphone is also provided proximate 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. Noise bursts are injected intermittently and the adaptation of the secondary path estimating adaptive filter controlled, so that the secondary path estimate can be maintained irrespective of the presence and amplitude of the source audio.
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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 a first anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; 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 ambient audio sounds at the transducer; a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds; a noise source for providing a noise signal; and a processing circuit that implements a first adaptive filter that generates a second anti-noise signal from the reference microphone signal, a secondary path adaptive filter having a secondary path response that shapes the source audio and a combiner that removes resulting shaped source audio from the error microphone signal to provide an error signal, wherein the processing circuit filters the error signal with a predetermined response to generate a filtered error signal and combines the second anti-noise signal with the filtered error signal to yield the first anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener in conformity with the error signal and the reference microphone signal, and wherein the processing circuit injects intermittent bursts of noise from the noise source into the secondary path adaptive filter and the audio signal reproduced by the transducer and permits the secondary path adaptive filter to adapt during the intermittent bursts of noise. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of countering effects of ambient audio sounds by a personal audio device, the method comprising:
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providing a reference microphone signal indicative of the ambient audio sounds; adaptively generating a first anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener in conformity with the error signal and the reference microphone signal, wherein the adaptively generating generates a second anti-noise signal from the reference microphone signal with a first adaptive filter; combining the anti-noise signal with source audio; providing a result of the combining to a transducer; measuring an acoustic output of the transducer and the ambient audio sounds with an error microphone; shaping the source audio with a secondary path adaptive filter having a secondary path response that shapes the source audio; removing resulting shaped source audio from the error microphone signal; filtering a result of the removing with a predetermined response to provide a filtered error signal; combining the second anti-noise signal with the filtered error signal to yield the first anti-noise signal; injecting intermittent bursts of noise from a noise source into the secondary path adaptive filter and the audio signal reproduced by the transducer; and permitting the secondary path adaptive filter to adapt during the intermittent bursts of noise. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. 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 a first anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; an error microphone input for receiving an error microphone signal indicative of the acoustic output of the transducer and ambient audio sounds at the transducer; a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds; a noise source for providing a noise signal; and a processing circuit that implements a first adaptive filter that generates a second anti-noise signal from the reference microphone signal, a secondary path adaptive filter having a secondary path response that shapes the source audio and a combiner that removes resulting shaped source audio from the error microphone signal to provide an error signal, wherein the processing circuit filters the error signal with a predetermined response to generate a filtered error signal and combines the second anti-noise signal with the filtered error signal to yield the first anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener in conformity with the error signal and the reference microphone signal, and wherein the processing circuit injects intermittent bursts of noise from the noise source into the secondary path adaptive filter and the audio signal reproduced by the transducer and permits the secondary path adaptive filter to adapt during the intermittent bursts of noise. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification