Speaker damage prevention in adaptive noise-canceling personal audio devices
First Claim
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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 the 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 that provides an error microphone signal indicative of the acoustic output of the transducer; and
a processing circuit within the housing for adaptively generating the anti-noise signal from the reference microphone signal such that the anti-noise signal causes substantial cancellation of the ambient audio sounds, and wherein the processing circuit further monitors a level of the anti-noise signal, determines that the anti-noise signal may cause damage to the transducer and adjusts the generation of the anti-noise signal such that damage to the transducer is prevented, and wherein the processing circuit implements an adaptive filter having a response that shapes the anti-noise signal to reduce the presence of the ambient audio sounds in the error microphone signal, and wherein the processing circuit, in response to determining that the anti-noise signal may cause damage to the transducer, freezes adaptation of the adaptive filter.
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Abstract
A personal audio device, such as a wireless telephone, includes noise canceling 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. A processing circuit monitors a level of the anti-noise signal, determines that the anti-noise signal may cause damage to the transducer and adjusts the generation of the anti-noise signal such that damage to the transducer is prevented.
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Citations
25 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 the 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 that provides an error microphone signal indicative of the acoustic output of the transducer; and a processing circuit within the housing for adaptively generating the anti-noise signal from the reference microphone signal such that the anti-noise signal causes substantial cancellation of the ambient audio sounds, and wherein the processing circuit further monitors a level of the anti-noise signal, determines that the anti-noise signal may cause damage to the transducer and adjusts the generation of the anti-noise signal such that damage to the transducer is prevented, and wherein the processing circuit implements an adaptive filter having a response that shapes the anti-noise signal to reduce the presence of the ambient audio sounds in the error microphone signal, and wherein the processing circuit, in response to determining that the anti-noise signal may cause damage to the transducer, freezes adaptation of the adaptive filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of preventing damage to a transducer of a personal audio device having adaptive noise canceling, the method comprising:
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measuring ambient audio sounds with a reference microphone; adaptively generating an anti-noise signal from a result of the measuring for countering the effects of ambient audio sounds in an acoustic output of the transducer; combining the anti-noise signal with a source audio signal; providing a result of the combining to a transducer; measuring the acoustic output of the transducer with an error microphone, wherein the adaptively generating implements an adaptive filter having a response that shapes the anti-noise signal to reduce the presence of the ambient audio sounds in the result of the measuring the acoustic output of the transducer; monitoring a level of the anti-noise signal; determining that the anti-noise signal may cause damage to the transducer; adjusting the anti-noise signal such that damage to the transducer is prevented; and in response to determining that the anti-noise signal may cause damage to the transducer, freezing adaptation of the adaptive filter. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. 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 acoustic output of the transducer; and a processing circuit for adaptively generating the anti-noise signal from the reference microphone signal such that the anti-noise signal causes substantial cancellation of the ambient audio sounds, and wherein the processing circuit further monitors a level of the anti-noise signal, determines that the anti-noise signal may cause damage to the transducer and adjusts the generation of the anti-noise signal such that damage to the transducer is prevented, wherein the processing circuit implements an adaptive filter having a response that shapes the anti-noise signal to reduce the presence of the ambient audio sounds in the error microphone signal, and wherein the processing circuit, in response to determining that the anti-noise signal may cause damage to the transducer, freezes adaptation of the adaptive filter. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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Specification