Acoustic in-ear detection for earpiece

1. An apparatus comprising:

at least two earpieces suitable to be applied at auditory openings of a user's ears, each of the earpieces comprising:

a speaker enabled to be supplied with an audio signal for rendering, and

a microphone arranged in vicinity of the speaker arranged to acquire a sound signal; and

a signal processor, wherein the signal processor is arranged to determine whether the earpieces are applied at the user's ears by analysis of the acquired sound signal,

wherein the analysis is based on the acoustic coupling of the audio signal from a speaker of one of the earpieces to a microphone of one of the earpieces,

wherein the acoustic coupling is between the speaker of one earpiece and the microphone of another earpiece.

2. The apparatus according to claim 1 , wherein the microphone of one of the earpieces is arranged to acquire a sound signal from sounds present inside an auditory opening of the user's ear when the earpiece is applied at the ear.

3. The apparatus according to claim 2 , wherein acoustic coupling also occurs between the speaker and the microphone of one or each earpiece.

4. The apparatus according to claim 1 , wherein the analysis is based on a propagation delay between the speaker of the one earpiece and the microphone of the another earpiece wherein the earpieces are determined to be applied if the propagation delay corresponds to a delay for propagating through a head.

5. The apparatus according to claim 1 , wherein an audio signal provided to the one earpiece comprises a sub-signal such that the sound signal acquirable at the another earpiece comprises a signal component emanating from sound provided at the user's other ear and which sound is modulatedly attenuated by pulsating blood of veins of the user when the sound propagates through the head of the user when the earpieces are applied, such that a heartbeat is extractable from the signal component to determine that the earpieces are applied.

6. The apparatus according to claim 5 , wherein the signal processor is arranged to extract the heartbeat by low pass filtering the sound signal in a low pass filter.

7. The apparatus according to claim 6 , wherein the low pass filter has a cutoff frequency between 3 and 10 Hz.

8. The apparatus according to claim 1 , wherein the audio signal provided to the one earpiece comprises a sub-signal comprising any of a tone in sub-sonic or ultra-sonic frequency, and a wideband pulse, and the signal processor is arranged to discriminate the acquired sound signal at the another earpiece to determine the acoustic coupling.

9. The apparatus according to claim 1 , wherein the microphone is arranged to acquire a sound signal from sounds present outside the earpiece.

10. The apparatus according to claim 9 , wherein acoustic coupling also occurs between the speaker and the microphone of one or each earpiece.

11. The apparatus according to claim 1 , further comprising an application arranged to control features of the application based on the determination whether the earpiece is applied or not.

12. The apparatus according to claim 11 , wherein the application is arranged to interrupt rendering associated with the audio signal when the signal processor has determined that the earpiece is not applied, and arranged to resume the rendering when the signal processor has determined that the earpiece is applied.

13. The apparatus according to claim 11 , wherein the application is arranged to establish communication associated with the audio signal when the signal processor has determined that the earpiece is applied, and arranged to terminate the communication when the signal processor has determined that the earpiece is not applied.

14. A method, for an apparatus comprising at least two earpieces suitable to be applied at a user's ears for rendering an audio signal in the user's ears when the earpieces are applied at the ears, each of the earpieces comprising a speaker enabled to be supplied with the audio signal for rendering and a microphone arranged in vicinity of the speaker, the method comprising

providing the audio signal to the speaker of one earpiece,

acquiring a sound signal by the microphone of another earpiece; and

determining by a signal processor whether one of the earpieces is applied at the user's ear by analyzing the sound signal based on acoustic coupling of the audio signal from the speaker of the one earpiece to the microphone of the another earpiece.

15. The method according to claim 14 , wherein the acquiring comprises acquiring a sound signal at a position of the earpiece such that sounds present inside an auditory opening of the user's ear are acquired when the earpiece is applied at the ear.

16. The method according to claim 15 , wherein acoustic coupling also occurs between the speaker and the microphone of one or each earpiece.

17. The method according to claim 14 , wherein the analyzing comprises determining a propagation delay between the speaker of the one earpiece and the microphone of the another earpiece wherein the earpieces are determined to be applied if the propagation delay corresponds to a delay for propagating through a head.

18. The method according to claim 14 , wherein the audio signal provided to the one earpiece comprises a sub-signal such that the sound signal acquirable at the another earpiece comprises a signal component emanating from sound provided at the user's other ear and which sound is modulatedly attenuated by pulsating blood of veins of the user when the sound propagates through the head of the user when the earpieces are applied, such that a heartbeat is extractable from the signal component to determine that the earpieces are applied.

19. The method according to claim 18 , further comprising extracting the heartbeat by low pass filtering the sound signal in a low pass filter.

20. The method according to claim 19 , wherein the low pass filter has a cutoff frequency between 3 and 10 Hz.

21. The apparatus according to claim 14 , wherein the providing of the audio signal to the one earpiece comprises providing a sub-signal comprising any of a tone in sub-sonic or ultra-sonic frequency, and a wideband pulse, and the analyzing comprises discriminating the acquired sound signal at the another earpiece to determine the acoustic coupling.

22. The method according to claim 14 , wherein the acquiring comprises acquiring a sound signal at a position of the earpiece such that sounds present outside the earpiece are acquired although the earpiece is applied at the ear.

23. The method according to claim 22 , wherein acoustic coupling also occurs between the speaker and the microphone of one or each earpiece.

24. The method according to claim 14 , further comprising controlling features of an application based on the determination.

25. The method according to claim 24 , further comprising

interrupting rendering associated with the audio signal when the signal processor has determined that the earpiece is not applied; and

resuming the rendering when the signal processor has determined that the earpiece is applied.

26. The method according to claim 24 , further comprising

establishing communication associated with the audio signal when the signal processor has determined that the earpiece is applied; and

terminating the communication when the signal processor has determined that the earpiece is not applied.

27. A non-transitory computer readable medium comprising program code comprising instructions which when executed cause a method to be performed, the method comprising:

supplying an audio signal to a speaker of at least one earpiece suitable to be applied at a user's ear for rendering the audio signal in the user's ear when the earpiece is applied at the ear;

acquiring a sound signal by a microphone of the earpiece arranged in vicinity of the speaker; wherein the supplying of the audio signal is made to one earpiece and the acquiring is made at another earpiece, and

determining whether the earpiece is applied at the user's ear by analysis of the acquired sound signal based on acoustic coupling of the audio signal from the speaker of the one earpiece to the microphone of the another earpiece.

28. The non-transitory computer readable medium according to claim 27 , wherein the analysis comprises determining a propagation delay between the speaker of the one earpiece and the microphone of the another earpiece wherein the earpieces are determined to be applied if the propagation delay corresponds to a delay for propagating through a head.

29. The non-transitory computer readable medium according to claim 27 , wherein the audio signal provided to the one earpiece comprises a sub-signal such that the sound signal acquirable at the another earpiece comprises a signal component emanating from sound provided at the user's other ear and which sound is modulatedly attenuated by pulsating blood of veins of the user when the sound propagates through the head of the user when the earpieces are applied, such that a heartbeat is extractable from the signal component to determine that the earpieces are applied.

30. The non-transitory computer readable medium according to claim 29 , further comprising instructions for extracting the heartbeat by low pass filtering the sound signal in a low pass filter.

31. The non-transitory computer readable medium according to claim 30 , wherein the low pass filter has a cutoff frequency between 3 and 10 Hz.

32. The non-transitory computer readable medium according to claim 27 , wherein the providing of the audio signal to the one earpiece comprises providing a sub-signal comprising any of a tone in sub-sonic or ultra-sonic frequency, and a wideband pulse, and the analyzing comprises discriminating the acquired sound signal at the another earpiece to determine the acoustic coupling.

33. The non-transitory computer readable medium according to claim 27 , wherein the acquiring comprises acquiring a sound signal at a position of the earpiece such that sounds present outside the earpiece are acquired although the earpiece is applied at the ear.

34. The non-transitory computer readable medium according to claim 27 , further comprising instructions for controlling features of an application based on the determination.

35. The non-transitory computer readable medium according to claim 34 , further comprising instructions for

interrupting rendering associated with the audio signal when the processor has determined that the earpiece is not applied; and

resuming the rendering when the processor has determined that the earpieces is applied.

36. The computer readable medium according to claim 34 , further comprising instructions for

establishing communication associated with the audio signal when the processor has determined that the earpiece is applied; and

terminating the communication when the processor has determined that the earpiece is not applied.