MONITORING OF SPEAKER IMPEDANCE TO DETECT PRESSURE APPLIED BETWEEN MOBILE DEVICE AND EAR

• US 20140270208A1
• Filed: 03/15/2013
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Application

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Miller, Antonio John, Su, Jie
• Granted Patent: US 9,467,776 B2
• Time in Patent Office: Days
• US Class Current: 381/59
• CPC Class Codes: H04R 2410/05 Noise reduction with a separate noise microphone
• CPC Class Codes: H04R 2499/11 Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

Coupling between a user'"'"'s ear and a speaker of a mobile device may be determined by measuring an impedance of the speaker. When the user presses the mobile device against the user'"'"'s ear, the speaker impedance changes as a result of loading in the speaker'"'"'s acoustic radiation impedance. The speaker impedance change may be correlated with the force applied by the user to the mobile device. The measured speaker impedance may be provided as feedback to an adaptive noise cancellation (ANC) algorithm to adjust the output at the speaker. For example, when the mobile device is removed from the user'"'"'s ear, the ANC algorithm may be muted.

Claims

1. A method, comprising:

calculating an impedance of a speaker of a mobile device; and

determining a force, applied by a user of the mobile device, that causes contact between the mobile device and the user based, at least in part, on the calculated impedance.

2. The method of claim 1, in which the impedance is an acoustic radiation impedance.

3. The method of claim 1, further comprising detecting, based at least in part on the determined force, when the mobile device is removed from an ear of the user.

4. The method of claim 1, further comprising:

applying a voltage to the speaker; and

measuring a current through the speaker,

in which the step of calculating the impedance comprises calculating the impedance based at least in part on the applied voltage and the measured current.

5. The method of claim 1, further comprising adjusting an adaptive noise cancellation (ANC) algorithm based, at least in part, on the determined force.

6. The method of claim 5, further comprising receiving an audio signal from an error microphone, in which the step of adjusting the ANC algorithm comprises adjusting the ANC algorithm based, at least in part, on the error microphone audio signal.

7. The method of claim 1, further comprising linearizing an output of the speaker based, at least in part, on the calculated impedance.

8. An apparatus, comprising:

a speaker;

an amplifier coupled to the speaker;

a processor coupled to the amplifier, in which the processor is configured to execute the steps comprising;

calculating an impedance of the speaker; and

determining an environmental load of the speaker based, at least in part, on the calculated impedance.

9. The apparatus of claim 8, in which the apparatus is a mobile device.

10. The apparatus of claim 9, in which the environmental load is proportional to a force, applied by a user of the mobile device, that causes contact between the mobile device and the user.

11. The apparatus of claim 10, in which the processor is further configured to detect, based at least in part on the determined force, when the mobile device is removed from an ear of the user.

12. The apparatus of claim 8, in which the amplifier is configured to:

apply a voltage to the speaker; and

measure a current through the speaker, and

in which the processor is configured to;

calculate the impedance based, at least in part, on the applied voltage and the measured current.

13. The apparatus of claim 8, in which the processor is a digital signal processor (DSP) and the digital signal processor is configured to adjust an adaptive noise cancellation (ANC) algorithm based, at least in part, on the determined force.

14. The apparatus of claim 13, further comprising:

an error microphone coupled to the digital signal processor,

in which the digital signal processor is further configured to adjust the ANC algorithm based, at least in part, on an audio signal received from the error microphone.

15. The apparatus of claim 8, in which the processor is further configured to linearize an output of the speaker based, at least in part, on the calculated impedance.

16. A computer program product, comprising:

a non-transitory computer readable medium comprising code to execute the steps comprising;

calculating an impedance of a speaker; and

determining an environmental load of the speaker based, at least in part, on the calculated impedance.

17. The computer program product of claim 16, in which the environmental load is proportional to a force, applied by a user of the mobile device, that causes contact between the mobile device and the user.

18. The computer program product of claim 16, in which the medium further comprises code to detect, based at least in part on the determined force, when the mobile device is removed from an ear of the user.

19. The computer program product of claim 16, in which the medium further comprises code to adjust an adaptive noise cancellation (ANC) algorithm based, at least in part, on the determined force.

20. The computer program product of claim 16, in which the medium further comprises code to linearize an output of the speaker based, at least in part, on the calculated impedance.