Voice activity detector (VAD) -based multiple-microphone acoustic noise suppression

• US 8,019,091 B2
• Filed: 09/18/2003
• Issued: 09/13/2011
• Est. Priority Date: 07/19/2000
• Status: Expired due to Term

• Current Assignee: Jawbone Innovations, LLC
• Original Assignee: AliphCom, Inc. (AliphCom Corp.)
• Inventors: Burnett, Gregory C., Breitfeller, Eric F.
• Primary Examiner(s): Goins; Davetta
• Assistant Examiner(s): LAO, LUN S
• Application Number:
  US10/667,207
• Publication Number:
  US 20040133421A1
• Time in Patent Office: 2,917 Days
• Field of Search: 381/70, 381 941- 947, 381/71.8, 381 91- 92, 381/122, 381/71.1, 704/200, 704/231, 704/233, 704/246, 704214-215
• US Class Current: 381/71.8
• CPC Class Codes: G10K 2210/30232 Transfer functions, e.g. impulse response
• CPC Class Codes: G10K 2210/3028 Filtering, e.g. Kalman filters or special analogue or digital filters
• CPC Class Codes: G10K 2210/3045 Multiple acoustic inputs, single acoustic output
• CPC Class Codes: G10L 19/0204 using subband decomposition
• CPC Class Codes: G10L 2021/02082 the noise being echo, reverberation of the speech
• CPC Class Codes: G10L 2021/02161 Number of inputs available containing the signal or the noise to be suppressed
• CPC Class Codes: G10L 2021/02165 Two microphones, one receiving mainly the noise signal and the other one mainly the speech signal
• CPC Class Codes: G10L 2021/02168 the estimation exclusively taking place during speech pauses
• CPC Class Codes: G10L 21/02 Speech enhancement, e.g. noise reduction or echo cancellation reducing echo effects in line transmission systems H04B3/20; echo suppression in hands-free telephones H04M9/08
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 21/0308 characterised by the type of parameter measurement, e.g. correlation techniques, zero crossing techniques or predictive techniques
• CPC Class Codes: G10L 21/0364 for improving intelligibility
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10
• CPC Class Codes: H04R 1/46 Special adaptations for use as contact microphones, e.g. on musical instrument, on stethoscope throat mountings H04R1/14

Abstract

Acoustic noise suppression is provided in multiple-microphone systems using Voice Activity Detectors (VAD). A host system receives acoustic signals via multiple microphones. The system also receives information on the vibration of human tissue associated with human voicing activity via the VAD. In response, the system generates a transfer function representative of the received acoustic signals upon determining that voicing information is absent from the received acoustic signals during at least one specified period of time. The system removes noise from the received acoustic signals using the transfer function, thereby producing a denoised acoustic data stream.

Claims

1. A method for removing noise from acoustic signals, comprising:

receiving at least two acoustic signals using at least two acoustic microphones positioned in a plurality of locations;

receiving a voice activity signal that includes information on vibration of human tissue associated with human voicing activity of a user;

generating a voice activity detection (VAD) signal using the voice activity signal;

generating at least two transfer functions representative of a ratio of energy of the acoustic signal received using at least two different acoustic microphones of the at least two acoustic microphones when the VAD indicates that user voicing activity is absent, wherein the at least two transfer functions comprise a first transfer function and a second transfer function; and

removing acoustic noise from at least one of the acoustic signals by applying the first transfer function and at least one combination of the first transfer function and the second transfer function to the acoustic signals and generating denoised acoustic signals.

2. The method of claim 1, wherein removing noise further comprises:

generating one transfer function of the at least two transfer functions to be representative of a ratio of energy of the acoustic signal received when the VAD indicates that user voice activity is present; and

removing noise from the acoustic signals using at least one combination of the at least two transfer functions to generate the denoised acoustic signals.

3. The method of claim 1, wherein the acoustic signals include at least one reflection of at least one associated noise source signal and at least one reflection of at least one acoustic source signal.

4. The method of claim 1, wherein generating the at least two transfer functions comprises recalculating the at least two transfer functions during at least one prespecified interval.

5. The method of claim 1, wherein generating the at least two transfer functions comprises use of at least one technique selected from a group consisting of adaptive techniques and recursive techniques.

6. The method of claim 1, wherein information on the vibration of human tissue is provided by a sensor in contact with the skin.

7. The method of claim 1, wherein information on the vibration of human tissue is provided via at least one sensor selected from among at least one of an accelerometer, a skin surface microphone in physical contact with skin of a user, a human tissue vibration detector, a radio frequency (RF) vibration detector, and a laser vibration detector.

8. The method of claim 1, wherein the human tissue is at least one of on a surface of a head, near the surface of the head, on a surface of a neck, near the surface of the neck, on a surface of a chest, and near the surface of the chest.

9. The method of claim 1, further comprising:

dividing acoustic data of the acoustic signals into a plurality of subbands;

generating a subband transfer function representative of the ratio of acoustic energies received in each microphone in each subband;

removing acoustic noise from each of the plurality of subbands using the subband transfer function, wherein a plurality of denoised acoustic subband signals are generated; and

combining the plurality of denoised acoustic subband signals to generate the denoised acoustic signal.

10. The method of claim 1, wherein the at least two acoustic microphones comprise a first directional acoustic microphone and a second directional acoustic microphone, wherein the first directional acoustic microphone and the second directional acoustic microphone selectively attenuate the acoustic signals based on the direction of arrival.

11. A system for removing acoustic noise from the acoustic signals, comprising:

a receiver that receives at least two acoustic signals via at least two acoustic microphones positioned in a plurality of locations;

at least one sensor that receives human tissue vibration information associated with human voicing activity of a user;

a processor coupled among the receiver and the at least one sensor that generates a plurality of transfer functions, wherein the plurality of transfer functions includes a first transfer function representative of a ratio of energy of acoustic signals received using at least two different acoustic microphones of the at least two acoustic microphones, wherein the first transfer function is generated in response to a determination that voicing activity is absent from the acoustic signals for a period of time, wherein the plurality of transfer functions includes a second transfer function representative of the acoustic signals, wherein the second transfer function is generated in response to a determination that voicing activity is present in the acoustic signals for the period of time, wherein acoustic noise is removed from the acoustic signals using the first transfer function and at least one combination of the first transfer function and the second transfer function to produce the denoised acoustic data stream.

12. The system of claim 11, wherein the sensor includes a mechanical sensor in contact with the skin.

13. The system of claim 11, wherein the sensor includes at least one of an accelerometer, a skin surface microphone in physical contact with skin of a user, a human tissue vibration detector, a radio frequency (RF) vibration detector, and a laser vibration detector.

14. The system of claim 11, wherein the human tissue is at least one of on a surface of a head, near the surface of the head, on a surface of a neck, near the surface of the neck, on a surface of a chest, and near the surface of the chest.

15. The system of claim 11, further comprising:

dividing acoustic data of the acoustic signals into a plurality of subbands;

generating a transfer function representative of the ratio of acoustic energies received in each microphone in each subband;

removing acoustic noise from each of the plurality of subbands using a transfer function, wherein a plurality of denoised acoustic data streams are generated; and

combining the plurality of denoised acoustic data streams to generate the denoised acoustic data stream.

16. The system of claim 11, wherein the receiver includes a plurality of independently located microphones.

17. The system of claim 11, wherein the at least two acoustic microphones comprise a first directional acoustic microphone and a second directional acoustic microphone, wherein the first directional acoustic microphone and the second directional acoustic microphone selectively attenuate the acoustic signals based on the direction of arrival.

18. A signal processing system coupled among a user and an electronic device, wherein the signal processing system includes a denoising subsystem for removing acoustic noise from acoustic signals, the denoising subsystem comprising a processor coupled among a receiver and at least one sensor, wherein the receiver is coupled to receive the acoustic signals via at least two microphones, wherein the at least one sensor detects human tissue vibration associated with human voicing activity of a user, wherein the processor generates a plurality of transfer functions, wherein a first transfer function representative of a ratio of acoustic energy received by the two microphones is generated in response to a determination that voicing activity is absent from the acoustic signals for a specified period of time, wherein a second transfer function representative of the acoustic signals is generated in response to a determination that voicing activity is present in the acoustic signals for a specified period of time, wherein acoustic noise is removed from the acoustic signals using the first transfer function and at least one combination of the first transfer function and the second transfer function to produce a denoised acoustic data stream.

19. The system of claim 18, wherein the at least one electronic device includes at least one of cellular telephones, personal digital assistants, portable communication devices, computers, video cameras, digital cameras, and telematics systems.

20. The system of claim 18, wherein the human tissue is at least one of on a surface of a head, near the surface of the head, on a surface of a neck, near the surface of the neck, on a surface of a chest, and near the surface of the chest.