Off-ear detector for personal listening device with active noise control
First Claim
1. A method for acoustic noise cancellation (ANC) in a personal listening device, comprising:
- performing an acoustic noise cancellation (ANC) process during in-the-field use of the personal listening device using an adaptive control filter to produce anti-noise by the personal listening device, the ANC process computing an adaptive path filter in accordance with an adaptive filter control algorithm, the adaptive path filter estimating a transfer function of a signal path between an earpiece speaker of the personal listening device and an error microphone that are configured to be located at a user'"'"'s ear;
making a first copy of the adaptive path filter;
detecting an off-ear condition using an adaptive path filter-based detection metric determined from information that is in the first copy of the adaptive path filter; and
one of a) slowing down or freezing adaptation of the adaptive control filter, or b) disabling the ANC process so as to power down the ANC process, in response to the off-ear condition being detected.
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Abstract
In a personal listening device, an ANC system can benefit from a mechanism to detect an off-ear condition, which may be a situation in which the user of the personal listening device has moved an earphone or handset housing away from her ear. A detector may detect such a condition using signals from a touch sensor and/or a vibration sensor that are integrated in the earphone or handset housing, and in response power down the ANC system, or in the case of an adaptive ANC system slow down, or even freeze, the adaptation of one or more adaptive filters. The detector may operate during for example a phone call or during media file playback. Other embodiments are also described.
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Citations
21 Claims
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1. A method for acoustic noise cancellation (ANC) in a personal listening device, comprising:
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performing an acoustic noise cancellation (ANC) process during in-the-field use of the personal listening device using an adaptive control filter to produce anti-noise by the personal listening device, the ANC process computing an adaptive path filter in accordance with an adaptive filter control algorithm, the adaptive path filter estimating a transfer function of a signal path between an earpiece speaker of the personal listening device and an error microphone that are configured to be located at a user'"'"'s ear; making a first copy of the adaptive path filter; detecting an off-ear condition using an adaptive path filter-based detection metric determined from information that is in the first copy of the adaptive path filter; and one of a) slowing down or freezing adaptation of the adaptive control filter, or b) disabling the ANC process so as to power down the ANC process, in response to the off-ear condition being detected. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A personal listening device comprising:
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an earpiece speaker that is configured to be located at a user'"'"'s ear; an error microphone that is configured to be located at the user'"'"'s ear; an acoustic noise cancellation (ANC) controller having an adaptive filter control engine that updates an adaptive control filter which produces an anti-noise signal when an ANC process is running, the ANC process computing an adaptive path filter in accordance with an adaptive filter control algorithm, the adaptive path filter estimating a transfer function of a signal path between the earpiece speaker and the error microphone, and making a first copy of the adaptive path filter; and an off-ear detector that uses an adaptive path filter-based detection metric determined from information that is in the first copy of the adaptive path filter, to declare an off-ear condition for the personal listening device, wherein the ANC controller responds to the declared off-ear condition by one of a) slowing down or freezing the updating of the adaptive control filter, or b) becoming deactivated so as to save power. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A personal listening device comprising:
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an earpiece speaker that is configured to be located at a user'"'"'s ear; an error microphone that is configured to be located at the user'"'"'s ear; an acoustic noise cancellation (ANC) controller having an adaptive filter control engine that updates an adaptive control filter which produces an anti-noise signal when an ANC process is running, the ANC process computing an adaptive path filter in accordance with an adaptive filter control algorithm, the adaptive path filter estimating a transfer function of a signal path between the earpiece speaker and the error microphone, and making a first copy of the adaptive path filter; and an on-ear detector that uses an adaptive path filter-based detection metric determined from information that is in the first copy of the adaptive path filter, to declare an on-ear condition for the personal listening device, wherein the ANC controller responds to the declared on-ear condition by one of a) speeding up or unfreezing the updating of the adaptive control filter, when the ANC process is running, or b) activating the ANC process, when the ANC process is not running. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification