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US 8,848,936 B2Granted
Speaker damage prevention in adaptive noise-canceling personal audio devices
AssigneeCirrus Logic, Inc.
InventorsNitin Kwatra, Jon D. Hendrix
Life of this patent
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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.
Claims25
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.
3 more elements
A method of preventing damage to a transducer of a personal audio device having adaptive noise canceling, the method comprising:
- 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.
7 more elements
An integrated circuit for implementing at least a portion of a personal audio device, comprising:
- 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.
2 more elements
Dependencies are inferred from the claim text.