Active noise cancellation decisions in a portable audio device
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;
a first microphone to pick up the ambient acoustic noise, wherein the ANC circuitry includes an adaptive filter that generates the anti-noise signal using a representation of the ambient acoustic noise as picked up by the first microphone;
noise measurement circuitry having a first input coupled to an output of a second microphone, a second input coupled to receive the audio signal and the anti-noise signal, a first filter that models the earpiece speaker and the second microphone, a differencing unit having a first input coupled to the output of the second microphone and a second input coupled to an output of the first filter, and a second filter that models the earpiece speaker and the second microphone, wherein the audio signal is to pass through the first and second filters and the anti-noise signal is to pass through the first filter and further wherein the second microphone is positioned closer to the earpiece speaker than the first microphone and is to pick up (a) sound emitted from the earpiece speaker and (b) the ambient acoustic noise; and
control circuitry coupled to receive an estimate of the ambient acoustic noise from the noise measurement circuitry and to deactivate the ANC circuitry in response to determining that an estimate of how much sound emitted from the earpiece speaker has been corrupted by said ambient acoustic noise, indicates insufficient corruption 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 noise level is greater than a threshold level of an audio artifact that could be induced by the ANC. Other embodiments are also described and claimed.
66 Citations
12 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; a first microphone to pick up the ambient acoustic noise, wherein the ANC circuitry includes an adaptive filter that generates the anti-noise signal using a representation of the ambient acoustic noise as picked up by the first microphone; noise measurement circuitry having a first input coupled to an output of a second microphone, a second input coupled to receive the audio signal and the anti-noise signal, a first filter that models the earpiece speaker and the second microphone, a differencing unit having a first input coupled to the output of the second microphone and a second input coupled to an output of the first filter, and a second filter that models the earpiece speaker and the second microphone, wherein the audio signal is to pass through the first and second filters and the anti-noise signal is to pass through the first filter and further wherein the second microphone is positioned closer to the earpiece speaker than the first microphone and is to pick up (a) sound emitted from the earpiece speaker and (b) the ambient acoustic noise; and control circuitry coupled to receive an estimate of the ambient acoustic noise from the noise measurement circuitry and to deactivate the ANC circuitry in response to determining that an estimate of how much sound emitted from the earpiece speaker has been corrupted by said ambient acoustic noise, indicates insufficient corruption by noise. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for performing a call using a portable audio communications device comprising:
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activating active noise cancellation (ANC) circuitry so that an anti-noise signal is output to control ambient acoustic noise during the call at an earpiece speaker of the portable audio communications device; passing a downlink speech signal of the call and the anti-noise signal through a first filter that models the earpiece speaker and an error microphone; computing an estimate of the ambient acoustic noise using the first filtered downlink speech signal and the first filtered anti-noise signal; passing the downlink speech signal of the call through a second filter that models the earpiece speaker and the error microphone; determining, using the computed ambient noise estimate and the second filtered downlink speech signal, that sound emitted from an earpiece speaker of the device is not being sufficiently corrupted by said ambient acoustic noise; and deactivating the ANC circuitry in response to the determination. - View Dependent Claims (8, 9, 10, 11)
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12. A method for performing a call using a portable audio communications device, comprising:
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a) determining that an estimate of how much sound emitted from an earpiece speaker of the device during the call has been corrupted by ambient acoustic noise, indicates sufficient corruption by noise; b) in response to the determination in a), activating active noise cancellation (ANC) circuitry so that an anti-noise signal is output to control the ambient acoustic noise during the call at an earpiece speaker of the portable audio communications device; b2) passing a downlink speech signal of the call and the anti-noise signal through a first filter that models the earpiece speaker and an error microphone; b3) computing an estimate of the ambient acoustic noise using the first filtered downlink speech signal and the first filtered anti-noise signal; b4) passing the downlink speech signal of the call through a second filter that models the earpiece speaker and the error microphone; c) determining , using the computed ambient noise estimate and the second filtered downlink speech signal, that sound emitted from the earpiece speaker during the call has not been corrupted by ambient acoustic noise; and d) deactivating the ANC circuitry in response to the determination in c).
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Specification