OFF-EAR AND ON-EAR HEADPHONE DETECTION

• US 20170013345A1
• Filed: 09/10/2015
• Published: 01/12/2017
• Est. Priority Date: 07/10/2015
• Status: Active Grant

• Current Assignee: Avnera Corporation (Skyworks Solutions Incorporated)
• Original Assignee: Avnera Corporation (Skyworks Solutions Incorporated)
• Inventors: Rathoud, Shankar, Kumar, Amit, Sorensen, Eric
• Granted Patent: US 9,967,647 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G10K 11/17823 Reference signals, e.g. ambient acoustic environment
• CPC Class Codes: G10K 11/17825 Error signals
• CPC Class Codes: G10K 11/17827 Desired external signals, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 11/17833 by using a self-diagnostic function or a malfunction prevention function, e.g. detecting abnormal output levels
• CPC Class Codes: G10K 11/17835 using detection of abnormal input signals
• CPC Class Codes: G10K 11/17853 of the filter
• CPC Class Codes: G10K 11/17855 for improving speed or power requirements
• CPC Class Codes: G10K 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone
• CPC Class Codes: G10K 11/17885 additionally using a desired external signal, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets
• CPC Class Codes: G10K 2210/3021 Eigenfrequencies; Eigenvalues, e.g. used to identify most significant couplings between actuators and sensors
• CPC Class Codes: H04R 1/1041 Mechanical or electronic switches, or control elements switches in general H01H
• CPC Class Codes: H04R 1/1083 Reduction of ambient noise active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06
• CPC Class Codes: H04R 2410/05 Noise reduction with a separate noise microphone
• CPC Class Codes: H04R 2460/03 Aspects of the reduction of energy consumption in hearing devices
• CPC Class Codes: H04R 29/00 Monitoring arrangements; Testing arrangements for hearing aids H04R25/30; detection of loudspeaker connection H04R5/04; sound-field adaptation dependent on speaker detection H04S7/308
• CPC Class Codes: H04R 3/00 Circuits for transducers , loudspeakers or microphones

Abstract

A headphone detector including a headphone and a processor. The headphone has a microphone and a speaker, and the microphone is configured to generate an audio signal based on an output of the speaker. The processor is configured to receive the audio signal, determine a characteristic of the audio signal, and assess whether the headphone is on ear or off ear based on a comparison of the characteristic to a threshold. In another aspect, an off-ear detection (OED) system includes a headphone and an OED processor. The headphone has a speaker, a feedforward microphone, and a feedback microphone. The OED processor is configured to determine whether the headphone is off ear or on ear, based at least in part on a headphone audio signal, a feedforward microphone signal, and a feedback microphone signal.

Claims

1. A headphone detector comprising:

a headphone having a microphone and a speaker, the microphone configured to generate an audio signal based on an output of the speaker; and

a processor configured to receive the audio signal, determine a characteristic of the audio signal, and assess whether the headphone is on ear or off ear based on a comparison of the characteristic to a threshold.

2. The headphone detector of claim 1, further comprising a tone source configured to produce a tone in the output of the speaker.

3. The headphone detector of claim 2, in which the microphone includes a feedback microphone configured to sample the output of the speaker.

4. The headphone detector of claim 3, further comprising a feedforward microphone configured to generate an ambient noise signal based on a sampled ambient noise level, in which the processor is further configured to receive the ambient noise signal, determine a characteristic of the ambient noise signal, and assess whether the headphone is on ear or off ear based on a comparison of the characteristic of the audio signal and the characteristic of the ambient noise signal to the threshold.

5. The headphone detector of claim 2, in which a signal generated by the tone source is mixed with the audio signal.

6. The headphone detector of claim 1, in which the characteristic of the audio signal is an energy of the audio signal.

7. The headphone detector of claim 1, in which the characteristic of the audio signal is an energy of a portion of the audio signal.

8. The headphone detector of claim 1, in which the characteristic of the audio signal is an energy of a low-frequency portion of the audio signal.

9. The headphone detector of claim 1, in which the threshold relates to a known condition of the headphone.

10. The headphone detector of claim 1, in which the microphone includes a feedback microphone configured to sample the output of the speaker, the headphone detector further comprising a feedforward microphone configured to generate an ambient noise signal based on a sampled ambient noise level, in which the processor is further configured to receive the ambient noise signal, determine a characteristic of the ambient noise signal, and assess whether the headphone is on ear or off ear further based on a comparison of the characteristic of the ambient noise signal to a parameter.

11. An off-ear detection (OED) system comprising:

a headphone having;

a speaker configured to transmit an audio playback signal based on a headphone audio signal,

a feedforward microphone configured to sense an ambient noise signal and transmit a feedforward microphone signal based at least in part on the ambient noise signal, and

a feedback microphone configured to sense a total audio signal and transmit a feedback microphone signal based at least in part on the total audio signal, in which the total audio signal is the sum of the audio playback signal and at least a portion of the ambient noise level; and

an OED processor configured to receive the headphone audio signal, the feedforward microphone signal, and the feedback microphone signal, the OED processor further configured to determine whether the headphone is off ear or on ear, based at least in part on the headphone audio signal, the feedforward microphone signal, and the feedback microphone signal.

12. The system of claim 11, further comprising a tone generator configured to inject a tone signal into the headphone audio signal.

13. The system of claim 12, in which the tone signal is configured to produce a tone at the speaker having a frequency of between about 15 Hz and about 30 Hz.

14. The system of claim 11, further comprising a bandpass filter configured to select a frequency of the headphone audio signal, a frequency of the feedforward microphone signal, and a frequency of the feedback microphone signal received by the OED processor.

15. The system of claim 14, in which the bandpass filter has a passband between about 15 Hz and about 30 Hz.

16. A method of detecting whether a headphone is off ear or on ear, the method comprising:

generating an audio signal based on an output of a speaker of a headphone;

receiving, at a processor, the audio signal;

determining, with the processor, a characteristic of the audio signal; and

assessing, by the processor, whether the headphone is on ear or off ear by comparing the characteristic to a threshold.

17. The method of claim 16, further comprising producing a tone at the speaker with a tone source.

18. The method of claim 17, further comprising mixing a signal from the tone source with the audio signal.

19. The method of claim 16, in which determining the characteristic of the audio signal includes determining an energy of the audio signal.

20. The method of claim 16, in which determining the characteristic of the audio signal includes determining an energy of a portion of the audio signal.

21. The method of claim 16, in which determining the characteristic of the audio signal includes determining an energy of a low-frequency portion of the audio signal.

22. The method of claim 16, in which comparing the characteristic to a threshold includes comparing the characteristic to a threshold relating to a known condition of the headphone.

23. A method of detecting whether a headphone is off ear or on ear, the method comprising:

producing an acoustic signal at a headphone based at least in part on a received headphone audio signal;

generating, at the headphone, a feedforward microphone signal and a feedback microphone signal, in which the feedback microphone signal is based at least in part on the acoustic signal;

determining, with the processor, a characteristic of the headphone audio signal, a characteristic of the feedforward microphone signal, and a characteristic of the feedback microphone signal; and

assessing, with the processor, whether the headphone is off ear or on ear based at least in part on the characteristic of the headphone audio signal, the characteristic of the feedforward microphone signal, and the characteristic of the feedback microphone signal.

24. The method of claim 23, further comprising injecting a tone signal into a headphone audio signal.

25. The method of claim 23, further comprising applying a bandpass filter to the headphone audio signal, the feedforward microphone signal, and the feedback microphone signal before determining the characteristics, the bandpass filter having a center frequency of less than 100 Hz.

26. The method of claim 23, further comprising iteratively receiving, at the processor, the headphone audio signal, the feedforward microphone signal, and the feedback microphone signal until a preset duration of samples is obtained.

27. The method of claim 26, in which determining the characteristics includes determining:

a running sum for each of the headphone audio signal, the feedforward microphone signal, and the feedback microphone signal;

a running sum of squares of the headphone audio signal, the feedforward microphone signal, and the feedback microphone signal; and

a running sum of products of the feedforward microphone signal times the feedback microphone signal.

28. The method of claim 23, further comprising outputting a decision signal from the processor, in which the decision signal is based at least in part on whether the headphone is assessed to be off ear or on ear.

29. The method of claim 28, further comprising triggering a convenience feature based at least in part on the decision signal.

30. The method of claim 29, in which the convenience feature includes sending a signal to initiate a power-saving feature.

31. The method of claim 29, in which the convenience feature includes sending a signal to stop a media player from generating the headphone audio signal.

32. The method of claim 29, in which the convenience feature includes sending a signal to start a media player, the media player generating the headphone audio signal.

33. The method of claim 23, further comprising iteratively performing the generating, determining, and assessing processes until a preset number of identical, consecutive assessments is obtained.

34. The method of claim 33, further comprising a delay period between each iteration, the delay period being substantially longer than a duration of time for performing one iteration of the generating, determining, and assessing processes.

35. The method of claim 33, further comprising injecting a tone signal into a headphone audio signal for each iteration after a preset number of iterations.

36. The method of claim 23, in which determining the characteristics includes determining an energy of the headphone audio signal, an energy of the feedforward microphone signal, and an energy of the feedback microphone signal.

37. The method of claim 23, in which determining the characteristics includes determining a power of the headphone audio signal, a power of the feedforward microphone signal, and a power of the feedback microphone signal.