Active noise cancellation decisions using a degraded reference
First Claim
1. A portable audio device comprising:
- an earpiece speaker having an input to receive an audio signal;
active noise cancellation (ANC) circuitry to provide an anti-noise signal at the input of the earpiece speaker to control ambient acoustic noise outside of the device that is heard by a user of the device; and
noise measurement circuitry having a first input coupled to an output of a first microphone and a second input coupled to receive the anti-noise signal and not the audio signal, the first microphone to pick up (a) sound emitted from the earpiece speaker and (b) the ambient acoustic noise, the noise measurement circuitry including a first filter that models the earpiece speaker and the first microphone, wherein the anti-noise signal and not the audio signal is to pass through the first filter, and a first differencing unit having a first input coupled to the output of the first microphone and a second input coupled to an output of the first filter, and an output that provides a degraded audio reference signal; and
control circuitry coupled to receive the degraded audio reference signal and to deactivate the ANC circuitry in response to using the degraded audio reference to determine that sound emitted from the earpiece speaker has not been sufficiently corrupted by noise.
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Abstract
Active noise cancellation (ANC) circuitry is coupled to the input of an earpiece speaker in a portable audio device, to control the ambient acoustic noise outside of the device and that may be heard by a user of the device. A microphone is to pickup sound emitted from the earpiece speaker, as well as the ambient acoustic noise. Control circuitry deactivates the ANC in response to determining that an estimate of how much sound emitted from the earpiece speaker has been corrupted by noise indicates insufficient corruption by noise. In another embodiment, the ANC decision is in response to determining that an estimate of the ambient acoustic noise level is greater than an estimate of the anti-noise produced by the ANC. Other embodiments are also described and claimed.
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Citations
17 Claims
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1. A portable audio device comprising:
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an earpiece speaker having an input to receive an audio signal; active noise cancellation (ANC) circuitry to provide an anti-noise signal at the input of the earpiece speaker to control ambient acoustic noise outside of the device that is heard by a user of the device; and noise measurement circuitry having a first input coupled to an output of a first microphone and a second input coupled to receive the anti-noise signal and not the audio signal, the first microphone to pick up (a) sound emitted from the earpiece speaker and (b) the ambient acoustic noise, the noise measurement circuitry including a first filter that models the earpiece speaker and the first microphone, wherein the anti-noise signal and not the audio signal is to pass through the first filter, and a first differencing unit having a first input coupled to the output of the first microphone and a second input coupled to an output of the first filter, and an output that provides a degraded audio reference signal; and control circuitry coupled to receive the degraded audio reference signal and to deactivate the ANC circuitry in response to using the degraded audio reference to determine that sound emitted from the earpiece speaker has not been sufficiently corrupted by noise. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for performing a call using a portable audio communications device comprising:
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activating active noise cancellation (ANC) circuitry to control ambient acoustic noise during the call using an anti-noise signal; computing a degraded reference, being an estimate of an audio signal containing downlink speech of the call that has been corrupted by the ambient acoustic noise, by removing a filtered version of the anti-noise signal from a microphone signal; determining that an estimate of how much sound emitted from an earpiece speaker of the device has been corrupted by said ambient acoustic noise indicates insufficient corruption by noise, using the degraded reference; and deactivating the ANC circuitry in response to the determination. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification