Active noise cancellation decisions in a portable audio device

A portable audio device comprising:

• an earpiece speaker having an input to receive an audio signal;
• active noise cancellation (ANC) circuitry coupled to 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
• control circuitry to compute strength of an audio artifact present in sound emitted from the earpiece speaker,
• wherein the control circuitry is to deactivate the ANC circuitry in response to determining that the audio artifact strength is greater than an estimated level of said ambient acoustic noise.

A method for performing a call using a portable audio communications device comprising:

• activating active noise cancellation (ANC) circuitry to control ambient acoustic noise during the call;
• 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;
• and
• deactivating the ANC circuitry in response to the determination.

A method for performing a call using a portable audio communications device, comprising:

• 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 to control the ambient acoustic noise during the call;
• and then
• c) determining that an estimate of how much sound emitted from the earpiece speaker during the call has been corrupted by ambient acoustic noise indicates insufficient corruption by noise;
• and
• d) deactivating the ANC circuitry in response to the determination in c).

A method for performing a call using a portable audio communications device, comprising:

• estimating ambient acoustic noise heard by a user of the portable communications device during the call;
• determining an audio artifact threshold which indicates strength of an audio artifact that could be induced by the ANC circuitry and heard by a user of the device after being emitted from an earpiece speaker of the device;
• and
• deactivating ANC circuitry during the call in response to the estimated noise level being less than the audio artifact threshold.

A portable audio device comprising:

• a mobile phone handset having integrated therein an earpiece speaker, the earpiece speaker having an input coupled to receive a downlink speech signal, and a detector that can indicate when the handset is being held against a user's ear and when it is not;
• active noise cancellation (ANC) circuitry coupled to 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
• ANC decision control circuitry coupled to the detector and the ANC circuitry, to deactivate the ANC circuitry when the detector indicates the handset is not being held against the user's ear.