HEADPHONE OFF-EAR DETECTION
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Abstract
Disclosed is a signal processor for headphone off-ear detection. The signal processor includes an audio output to transmit an audio signal toward a headphone speaker in a headphone cup. The signal processor also includes a feedback (FB) microphone input to receive a FB signal from a FB microphone in the headphone cup. The signal processor also includes an off-ear detection (OED) signal processor to determine an audio frequency response of the FB signal over an OED frame as a received frequency response. The OED processor also determines an audio frequency response of the audio signal times an off-ear transfer function between the headphone speaker and the FB microphone as an ideal off-ear response. A difference metric si generated comparing the received frequency response to the ideal off-ear frequency response. The difference metric is employed to detect when the headphone cup is disengaged from an ear.
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Citations
31 Claims
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1-11. -11. (canceled)
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12. An off-ear detection circuit comprising:
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a tone generator configured to inject a tone signal into an audio signal to obtain a combined signal that includes the tone signal and the audio signal, the tone signal within a sub-audible frequency for a user; a feedback microphone input configured to receive a feedback signal based at least in part on the combined signal; and an off-ear detection processor configured to determine a received frequency response based on the feedback signal, determine a difference metric between the received frequency response and a modeled off-ear frequency response, and determine an off-ear state of a device based at least in part on the difference metric. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. An electronic device comprising:
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a speaker configured to output one or more of an audio signal or a tone signal; a tone generator configured to generate the tone signal, the tone signal within a frequency band that is not audible to a user; a feedback microphone configured to generate a feedback signal based at least in part on one or more of the audio signal or the tone signal; and an off-ear detection processor configured to determine a received frequency response based on the feedback signal, determine a difference metric between the received frequency response and a modeled off-ear frequency response, and determine an off-ear state of the electronic device based at least in part on the difference metric. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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29. A method of device off-ear detection comprising:
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generating a tone signal within a frequency band that is not audible to a user; combining the tone signal with an audio signal to obtain a combined signal; outputting, via a speaker of a device, the combined signal; receiving, via a feedback microphone of the device, a feedback signal generated based at least in part on the combined signal; determining a received frequency response based on the feedback signal; determining a difference metric between the received frequency response and a modeled off-ear frequency response; and detecting an off-ear state of the device using the difference metric. - View Dependent Claims (30, 31)
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Specification