Microphone-based orientation sensors and related techniques

• US 9,736,578 B2
• Filed: 06/07/2015
• Issued: 08/15/2017
• Est. Priority Date: 06/07/2015
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Iyengar, Vasu, Atkins, Joshua D, Pruthi, Tarun, Deshpande, Ashrith, Lindahl, Aram M.
• Primary Examiner(s): TRAN, THANG V
• Application Number:
  US14/732,770
• Publication Number:
  US 20160360314A1
• Time in Patent Office: 800 Days
• CPC Class Codes: G10L 2021/02166 Microphone arrays; Beamforming
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: H04R 1/406 microphones
• CPC Class Codes: H04R 2430/20 Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic H04R2203/12 takes precedence
• 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

An orientation detector can have a first microphone, a second microphone, and a reference microphone spaced from the first microphone and the second microphone. An orientation processor can be configured to determine an orientation of the first microphone, the second microphone, or both, relative to a user'"'"'s mouth based on a comparison of a relative strength of a first signal associated with the first microphone to a relative strength of a second signal associated with the second microphone. A channel selector in a speech enhancer can select one signal from among several signals based at least in part on the orientation determined by the orientation processor. A mobile communication handset can include a microphone-based orientation detector of the type disclosed herein.

Claims

1. An orientation detector comprising:

a first microphone transducer having a first position, a second microphone transducer having a second position, and a reference microphone transducer spaced from the first microphone transducer and the second microphone transducer, wherein each microphone transducer is configured to emit a respective signal in correspondence with an acoustic signal received by the respective microphone transducer;

a separation unit; and

an orientation processor configured to determine an orientation of the first microphone transducer, the second microphone transducer, or both, relative to a source of the acoustic signal based on a comparison of a first computed signal-separation associated with the first microphone transducer and the reference microphone transducer to a second computed signal-separation associated with the second microphone transducer and the reference microphone transducer;

wherein the separation unit generates the first computed signal-separation and the second computed signal-separation.

2. The orientation detector according to claim 1, wherein the first computed signal-separation corresponds, at least in part, to a signal emitted by the first microphone transducer.

3. The orientation detector according to claim 2, wherein the first computed signal-separation further corresponds to a combination of the signal emitted by the first microphone transducer with a signal emitted by the second microphone transducer, wherein at least a portion of the signal emitted by the first microphone transducer is more heavily weighted in the combination relative to at least a portion of the signal emitted by the second microphone transducer.

4. The orientation detector according to claim 2, wherein the second computed signal-separation corresponds, at least in part, to a signal emitted by the second microphone transducer.

5. The orientation detector according to claim 4, wherein the second computed signal-separation further corresponds to a combination of the signal emitted by the second microphone transducer with a signal emitted by the first microphone transducer, wherein at least a portion of the signal emitted by the second microphone transducer is more heavily weighted in the combination relative to at least a portion of the signal emitted by the first microphone transducer.

6. The orientation detector according to claim 1, wherein a measure of the first computed signal-separation associated with -the first microphone transducer and the reference microphone transducer comprises a difference in spectral power as between a signal emitted by the first microphone transducer and a signal emitted by the reference microphone transducer, and a measure of the second computed-signal separation associated with the second microphone transducer and the reference microphone transducer comprises a difference in spectral power as between a signal emitted by the second microphone transducer and the signal emitted by the reference microphone transducer.

7. The orientation detector according to claim 1, further comprising:

a separation processor configured to determine a spectral power separation, relative to a signal emitted by the reference microphone transducer, of a signal emitted by the first microphone transducer, a signal emitted by the second microphone transducer, a first beam comprising the signal emitted by the first microphone transducer and the signal emitted by the second microphone transducer, and a second beam comprising the signal emitted by the first microphone transducer and the signal emitted by the second microphone transducer,

the source of the acoustic signal, and a directionality of the second beam corresponds to a second direction of rotation relative to the source of the acoustic signal.

8. The orientation detector according to claim 7, further comprising a voice-activity-detector configured to declare voice activity when the spectral power separation of at least one of the signal emitted by the first microphone transducer, the signal emitted by the second microphone transducer, the first beam, and the second beam exceeds a threshold spectral power separation.

9. The orientation detector according to claim 8, wherein the threshold spectral power separation varies inversely with a level of stationary noise.

10. The orientation detector according to claim 1, wherein an axis extends from the first microphone transducer to the second microphone transducer, and wherein the orientation processor is further configured to determine an extent of rotation of the axis relative to a neutral position based on the comparison of the first computed signal-separation to the first computed signal-separation.

11. The orientation detector according to claim 1, further comprising one or more of a gyroscope, an accelerometer, and a proximity detector and a communication connection between the orientation processor and the one or more of the gyroscope, the accelerometer, and the proximity detector, wherein the orientation processor determines the orientation based at least in part on an output from the one or more of the gyroscope, the accelerometer, and the proximity detector.

12. The orientation detector according to claim 1, wherein the orientation is one of pitch, yaw, or roll, the orientation detector further comprising a fourth microphone transducer spaced apart from the first microphone transducer, the second microphone transducer and the reference microphone transducer, wherein the orientation processor is further configured to determine an angular rotation in the other two of pitch, yaw, and roll, based at least in part based on a comparison of a third computed signal-separation associated with the fourth microphone transducer and another of the microphone transducers to the first computed signal-separation, the second computed signal-separation, or both, wherein the separation unit generates the third computed signal-separation.

13. A communication handset comprising:

a chassis having a front side, a back side, a top edge, and a bottom edge;

a first microphone and a second microphone spaced apart from the first microphone, wherein the first and the second microphones are positioned on or adjacent to the bottom edge of the chassis;

a reference microphone facing the back side of the chassis and positioned closer to the top edge than to the bottom edge; and

an orientation detector configured to detect an orientation of the chassis relative to an acoustic source based at least in part on a strength of a signal from the first microphone relative to a signal from the reference microphone compared to a strength of a signal from the second microphone relative to the signal from the reference microphone.

14. The communication handset according to claim 13, further comprising a noise suppressor and a signal selector configured to direct to the noise suppressor a selected one of the signal from the first microphone, the signal from the second microphone, an average of the signal from the first microphone and the signal from the second microphone, a first beam comprising a first combination of the signal from the first microphone with the signal from the second microphone, and a second beam comprising a second combination of the signal from the first microphone and the signal from the second microphone, wherein a directionality of the first beam corresponds to a first direction of rotation relative to the acoustic source and a directionality of the second beam corresponds to a second direction of rotation relative to the acoustic source.

15. The communication handset according to claim 14, wherein the selector is configured to equalize a signal from the reference microphone to match a far-field response of the first beam signal, the second beam signal, or both, in diffuse noise.

16. The communication handset according to claim 14, wherein the noise suppressor is configured to subject the signal from the reference microphone to a minimum spectral profile corresponding to a system spectral noise profile of one or both of the first beam and the second beam.

17. The communication handset according to claim 13, further comprising one or more of a gyroscope, an accelerometer, and a proximity detector and a communication connection between the orientation detector and the one or more of the gyroscope, the accelerometer, and the proximity detector for resolving the orientation of the chassis relative to a fixed frame of reference.

18. The communication handset according to claim 13, further comprising a calibration data store containing a correlation between an angle of the chassis relative to a selected acoustic source and the strength of the signal from the first microphone compared to the strength of the signal from the second microphone, wherein the orientation detector is further configured to detect the orientation of the chassis relative to the acoustic source based at least in part on the correlation.

19. The communication handset according to claim 13, wherein a measure of the orientation of the chassis relative to the acoustic source comprises an extent of rotation from a neutral position, wherein the acoustic source is substantially centered between the first microphone and the second microphone in the neutral position.

20. The communication handset according to claim 13, further comprising a fourth microphone spaced apart from the bottom edge of the chassis, wherein the orientation detector is further configured to determine an angular rotation in each of pitch, yaw, and roll, based at least in part on a strength of a signal from the fourth microphone relative to a signal from the reference microphone.