Processing audio signals

• US 9,210,504 B2
• Filed: 12/30/2011
• Issued: 12/08/2015
• Est. Priority Date: 11/18/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Skype S.Ã R.L. (Microsoft Corporation)
• Inventors: Sorensen, Karsten Vandborg
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): Suthers, Douglas
• Application Number:
  US13/341,607
• Publication Number:
  US 20130129100A1
• Time in Patent Office: 1,439 Days
• Field of Search: 381/66, 381/92, 379/406.01, 379/406.06
• US Class Current: 1/1
• CPC Class Codes: H04M 3/002 Applications of echo suppressors or cancellers in telephonic connections in two-way loud-speaking telephone systems H04M9/08, echo suppressors or cancellers per se H04B3/20
• CPC Class Codes: H04M 9/082 using echo cancellers echo cancellers per se H04B3/23
• 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 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407
• CPC Class Codes: H04R 3/02 for preventing acoustic reaction , i.e. acoustic oscillatory feedback specially adapted for hearing aids H04R25/453

Abstract

In an embodiment, a method of processing audio signals at a device includes receiving audio signals at a plurality of microphones of the device; processing at least one of the audio signals received by the plurality of microphones to generate a first characteristic; a beamformer applying beamformer coefficients to the received audio signals, thereby generating a beamformer output; processing the beamformer output to generate a second characteristic. An echo canceller is applied to the beamformer output, thereby suppressing, from the beamformer output, an echo resulting from audio signals output from an audio output. An operating parameter of the echo canceller is determined, using a relationship between the first and second characteristics.

Claims

1. A method of processing audio signals at a device, the device comprising an audio output for outputting audio signals, the method comprising:

receiving audio signals at a plurality of microphones of the device;

processing at least one of the audio signals received by the plurality of microphones to generate a first characteristic;

a beamformer applying beamformer coefficients to the received audio signals, thereby generating a beamformer output;

processing the beamformer output to generate a second characteristic;

applying an echo canceller to the beamformer output, thereby suppressing, from the beamformer output, an echo resulting from audio signals output from the audio output; and

determining an operating parameter of the echo canceller based, at least in part, on a relationship between the first and second characteristics.

2. The method of claim 1 wherein each characteristic comprises a power spectrum, and the relationship defines a beamformer gain spectrum.

3. The method of claim 1 wherein each characteristic has a coefficient in each of a plurality of frequency bands, the relationship being determined for each frequency band.

4. The method of claim 1 wherein the relationship is a ratio of the first characteristic to the second characteristic.

5. The method of claim 1, comprising adapting an estimate of an echo path from the audio output to the plurality of microphones, prior to applying the echo canceller.

6. The method of claim 5, wherein adapting the estimate is carried out on the received audio signals.

7. The method of claim 5, wherein a beamformer gain spectrum based, at least in part, on the relationship, is applied to the output of the beamformer to generate a synthesized signal, wherein adapting the estimate is carried out on the synthesized signal.

8. The method of claim 5, wherein adapting the estimate comprises generating an echo path estimate using the audio signals supplied to the audio output.

9. The method of claim 1, further comprising:

estimating an echo path gain based, at least in part, on at least one of the audio signals received by the plurality of microphones;

estimating an echo in the beamformer output based, at least in part, on the estimated echo path gain and the relationship between the first and said characteristics; and

using the estimated echo in the beamformer output to determine said operating parameter.

10. The method of claim 1, comprising:

measuring an echo path gain based, at least in part, on at least one of the audio signals received by the plurality of microphones; and

using said measured echo path gain to determine an estimate of the echo power in the beamformer output, wherein said operating parameter is determined based on the estimate of the echo power in the beamformer output, and then modified based on said relationship between the first and second characteristics.

11. The method of claim 5 wherein a beamformer gain spectrum based, at least in part, on the relationship, is applied to the output of the beamformer to generate a synthesized signal, wherein the operating parameter is controlled based on the synthesized signal.

12. The method of claim 1 wherein said operating parameter comprises a level of echo suppression which is applied by the echo canceller to the beamformer output.

13. The method of claim 1 further comprising adapting said beamformer coefficients of the beamformer based on an analysis of the received audio signals.

14. A device for processing audio signals, the device comprising:

an audio output for outputting audio signals;

a plurality of microphones for receiving audio signals;

a beamformer configured to apply beamformer coefficients to the received audio signals, to thereby generate a beamformer output;

an echo canceller configured to be applied to the beamformer output, to thereby suppress, from the beamformer output, an echo resulting from audio signals output from the audio output; and

a processor configured to;

generate a first characteristic of at least one audio signal received by the plurality of microphones;

generate a second characteristic of the beamformer output; and

determine an operating parameter of the echo canceller based, at least in part, on a relationship between the first and second characteristics.

15. The device of claim 14 wherein said echo canceller comprises echo suppression arranged to be applied to the beamformer output, the echo suppression comprising a spectral analysis function.

16. The device of claim 15 wherein the processor operates to apply the spectral analysis function for generating the first and second characteristics.

17. The device of claim 16 wherein the processor comprises a ratio function for providing the relationship.

18. The device of claim 15 wherein the processor comprises a divide function for applying the relationship to the output of the beamformer for generating a synthesized signal.

19. A device of claim 14, wherein said processor is further configured to enable the device to:

estimate an echo path gain from at least one audio signal received by the plurality of microphones;

estimate an echo in the beamformer output based, at least in part, on the estimated echo path gain and the relationship between the first and second characteristics; and

determine said operating parameter based on the estimate of the echo power in the beamformer output.

20. The device of claim 14, wherein said processor is further configured to enable the device to:

measure an echo path gain from the at least one of the audio signals received by the plurality of microphones;

use said measured echo path gain to determine an estimate of the echo power in the beamformer output, wherein said operating parameter is determined based on the estimate of the echo power in the beamformer output; and

modify the thus determined operating parameter based on said relationship between the first and second characteristics.

21. A computer program product for processing audio signals at a device, the device comprising a plurality of microphones for receiving audio signals and an audio output for outputting audio signals, the computer program product being embodied on one or more computer-readable hardware memory devices and configured so as, responsive to execution by at least one processor of the device, to enable the device to perform operations comprising:

receiving audio signals at a plurality of microphones of the device;

processing at least one of the audio signals received by the plurality of microphones to generate a first characteristic;

a beamformer applying beamformer coefficients to the received audio signals, thereby generating a beamformer output;

processing the beamformer output to generate a second characteristic;

applying an echo canceller to the beamformer output, thereby suppressing, from the beamformer output, an echo resulting from audio signals output from the audio output; and

determining an operating parameter of the echo canceller based on a relationship between the first and second characteristics.