Low-latency multi-driver adaptive noise canceling (ANC) system for a personal audio device
First Claim
1. A personal audio system, comprising:
- a source of audio for reproduction, wherein the source of audio provides a source audio signal;
a first transducer for reproducing high-frequency content of the source audio signal 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 first transducer;
a second transducer for reproducing low-frequency content of the source audio signal for playback to the listener and a second anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the second transducer;
at least one microphone for providing at least one microphone signal indicative of the ambient audio sounds; and
a processing circuit that generates the first anti-noise signal from the at least one microphone signal using a first filter to reduce the presence of the ambient audio sounds at the first transducer and the second transducer in conformity with the at least one microphone signal, wherein the processing circuit generates the second anti-noise signal from the at least one microphone signal using a second filter to reduce the presence of the ambient audio sounds at the first transducer and the second transducer in conformity with the at least one microphone signal, wherein the processing circuit receives the source audio signal and filters the source audio signal to provide a crossover that generates a higher-frequency content source audio signal and a lower-frequency content source audio signal, and wherein the processing circuit further combines the higher-frequency content source audio signal with the first anti-noise signal and combines the lower-frequency content source audio signal with the second anti-noise signal.
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Abstract
A personal audio device including multiple output transducers for reproducing different frequency bands of a source audio signal, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal for each of the transducers from at least one microphone signal that measures the ambient audio to generate anti-noise signals. The anti-noise signals are generated by separate adaptive filters such that the anti-noise signals cause substantial cancellation of the ambient audio at their corresponding transducers. The use of separate adaptive filters provides low-latency operation, since a crossover is not needed to split the anti-noise into the appropriate frequency bands. The adaptive filters can be implemented or biased to generate anti-noise only in the frequency band corresponding to the particular adaptive filter. The anti-noise signals are combined with source audio of the appropriate frequency band to provide outputs for the corresponding transducers.
276 Citations
24 Claims
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1. A personal audio system, comprising:
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a source of audio for reproduction, wherein the source of audio provides a source audio signal; a first transducer for reproducing high-frequency content of the source audio signal 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 first transducer; a second transducer for reproducing low-frequency content of the source audio signal for playback to the listener and a second anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the second transducer; at least one microphone for providing at least one microphone signal indicative of the ambient audio sounds; and a processing circuit that generates the first anti-noise signal from the at least one microphone signal using a first filter to reduce the presence of the ambient audio sounds at the first transducer and the second transducer in conformity with the at least one microphone signal, wherein the processing circuit generates the second anti-noise signal from the at least one microphone signal using a second filter to reduce the presence of the ambient audio sounds at the first transducer and the second transducer in conformity with the at least one microphone signal, wherein the processing circuit receives the source audio signal and filters the source audio signal to provide a crossover that generates a higher-frequency content source audio signal and a lower-frequency content source audio signal, and wherein the processing circuit further combines the higher-frequency content source audio signal with the first anti-noise signal and combines the lower-frequency content source audio signal with the second anti-noise signal. - 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 system, the method comprising:
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measuring ambient audio sounds with at least one microphone to produce at least one microphone signal; first generating a first anti-noise signal from the at least one microphone signal using a first filter to reduce the presence of the ambient audio sounds at the first transducer in conformity with the at least one microphone signal; second generating a second anti-noise signal from the at least one microphone signal using a second filter to reduce the presence of the ambient audio sounds at the second transducer in conformity with the at least one microphone signal; providing a source of audio for reproduction, wherein the source of audio provides a source audio signal; receiving the source audio signal and filtering the source audio signal to implement a crossover that generates a higher-frequency content source audio signal and a lower-frequency content source audio signal; combining the higher-frequency content source audio signal with the first anti-noise signal; combining the lower-frequency content source audio signal with the second anti-noise reproducing high-frequency content of the source audio signal and the first anti-noise signal with the first transducer; and reproducing low-frequency content of the source audio signal and the second anti-noise signal with the second transducer. - 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 system, comprising:
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a source of audio for reproduction, wherein the source of audio provides a source audio signal; a first output for providing a first output signal to a first transducer for reproducing high-frequency content of the source audio signal and a first anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the first transducer; a second output for providing a second output signal to a second transducer for reproducing low-frequency content of the source audio signal including both second source audio for playback to a listener and a second anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the second transducer; at least one microphone input for providing at least one microphone signal indicative of the ambient audio sounds; and a processing circuit that generates the first anti-noise signal from the at least one microphone signal using a first filter to reduce the presence of the ambient audio sounds at the first transducer and the second transducer in conformity with the at least one microphone signal, wherein the processing circuit generates the second anti-noise signal from the at least one microphone signal using a second filter to reduce the presence of the ambient audio sounds at the first transducer and the second transducer in conformity with the at least one microphone signal, wherein the processing circuit receives the source audio signal and filters the source audio signal to provide a crossover that generates a higher-frequency content source audio signal and a lower-frequency content source audio signal, and wherein the processing circuit further combines the higher-frequency content source audio signal with the first anti-noise signal and combines the lower-frequency content source audio signal with the second anti-noise signal. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification