Headphone off-ear detection

A signal processor circuit assembly for off-ear headphone detection comprising:

• an audio generator configured to generate a tone signal at a specified bin, the tone signal included in an audio signal transmitted toward a headphone speaker;
• a feedback microphone input to receive a feedback signal from a feedback microphone in a headphone, the feedback signal based in part on the audio signal including the tone signal;
• and
• an off ear detection processor configured to determine a received frequency response from the feedback signal, determine a difference metric between the received frequency response and a modeled off-ear frequency response, and use the difference metric to detect when the headphone is in an off-ear state.

A method of headphone off-ear detection comprising:

• generating a tone signal at a specified frequency;
• including the generated tone signal in an audio signal transmitted toward a headphone speaker;
• receiving a feedback signal from a feedback microphone in a headphone, the feedback signal based in part on the audio signal;
• determining a received frequency response from the feedback signal;
• determining a difference metric between the received frequency response and a modeled off-ear frequency response, the difference metric based in part on the tone signal;
• and
• detecting when the headphone is in an off-ear state using the difference metric.

A headphone system comprising:

• a speaker;
• an audio generator configured to generate a tone signal at a specified frequency bin, the tone signal included in an audio signal transmitted to the a speaker;
• a feedback microphone positioned in the headphone, the feedback microphone configured to generate a feedback signal based in part on the audio signal;
• an off ear detection processor coupled to the feedback microphone, the off ear detection processor configured to determine a received frequency response from the feedback signal, determine a difference metric between the received frequency response and a modeled off-ear frequency response, and use the difference metric to detect when the headphone is in an off-ear state.