Processing Audio Signals

• US 20130013303A1
• Filed: 08/18/2011
• Published: 01/10/2013
• Est. Priority Date: 07/05/2011
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Skype Limited (Microsoft Corporation)
• Inventors: Strmmer, Stefan, SRENSEN, Karsten Vandborg
• Granted Patent: US 9,269,367 B2
• Time in Patent Office: Days
• US Class Current: 704/226
• CPC Class Codes: G10L 2021/02166 Microphone arrays; Beamforming
• 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

Abstract

A method of processing audio signals during a communication session between a user device and a remote node, includes receiving a plurality of audio signals at audio input means at the user device including at least one primary audio signal and unwanted signals and receiving direction of arrival information of the audio signals at a noise suppression means. Known direction of arrival information representative of at least some of said unwanted signals is provided to the noise suppression means and the audio signals are processed at the noise suppression means to treat as noise, portions of the signal identified as unwanted dependent on a comparison between the direction of arrival information of the audio signals and the known direction of arrival information.

Claims

1. A method of processing audio signals during a communication session between a user device and a remote node, the method comprising:

receiving a plurality of audio signals at the user device including at least one primary audio signal and unwanted signals;

receiving direction of arrival information of the audio signals at a noise reduction stage;

providing to the noise reduction stage known direction of arrival information representative of at least some of said unwanted signals; and

processing the audio signals at the noise reduction stage to treat as noise, portions of the signal identified as unwanted dependent on a comparison between the direction of arrival information of the audio signals and the known direction of arrival information.

2. The method according to claim 1, wherein the method further comprises:

estimating at least one principal direction from which the at least one primary audio signal is received at a beamformer at the user device; and

processing the plurality of audio signals to generate a single channel audio output signal, said processing comprising substantially suppressing audio signals from any direction other than the principal direction.

3. The method according to claim 2, wherein the single channel audio output signal comprises a sequence of frames, the noise reduction stage processing each of said frames in sequence.

4. The method according to claim 3, wherein direction of arrival of information for a principal signal component of a current frame being processed is received at the noise reduction stage, the method further comprising:

comparing the direction of arrival of information for the principal signal component of the current frame and the known direction of arrival information.

5. The method according to claim 4, wherein the known direction of arrival information includes at least one direction from which far-end signals are received at the beamformer.

6. The method according to claim 4, wherein the known direction of arrival information includes at least one classified direction, the at least one classified direction being a direction from which at least one unwanted audio signal arrives at the beamformer and is identified based on the signal characteristics of the at least one unwanted audio signal.

7. The method according to claim 4, wherein the known direction of arrival information includes at least one principal direction from which the at least one primary audio signal is received at the beamformer.

8. The method according to claim 4, wherein the beamformer processes the plurality of audio signals to generate the single channel audio output signal, the known direction of arrival information further includes the beam pattern of the beamformer.

9. The method according to claim 4, further comprising:

determining whether the principal signal component of the current frame is an unwanted signal based on said comparison; and

applying maximum attenuation to the current frame being processed if it is determined that the principal signal component of the current frame is an unwanted signal.

10. The method according to claim 9, further comprising determining that the principal signal component of the current frame is an unwanted signal if:

the principal signal component is received at the beamformer from at least one direction from which far-end signals are received at the beamformer;

or

the principal signal component is received at the beamformer from at least one classified direction;

or

the principal signal component is not received at the beamformer from at least one principal direction.

11. The method according to claim 4, further comprising:

receiving the plurality of audio signals and information on the at least one principal direction at signal processing circuitry;

processing the plurality of audio signals at the signal processing circuitry using said information on the at least one principal direction to provide additional information to the noise reduction stage; and

applying a level of attenuation to the current frame being processed at the noise reduction stage in dependence on said additional information and said comparison.

12. The method according to claim 4, further comprising:

receiving the single channel audio output signal and information on the at least one principal direction at signal processing circuitry;

processing the single channel audio output signal at the signal processing circuitry using said information on the at least one principal direction to provide additional information to the noise reduction stage; and

applying a level of attenuation to the current frame being processed at the noise reduction stage in dependence on said additional information and said comparison.

13. The method according to claim 11, wherein the additional information includes an indication on the desirability of the principal signal component of the current frame.

14. The method according to claim 11, wherein the additional information includes a power level of the principal signal component of the current frame relative to an average power level of the at least one primary audio signal.

15. The method according to claim 11, wherein the additional information includes a signal classification of the principal signal component of the current frame.

16. The method according to claim 11, wherein the additional information includes at least one direction from which the principal signal component of the current frame is received at the beamformer.

17. A user device for processing audio signals during a communication session between the user device and a remote node, the user device comprising:

a beamformer configured to receive a plurality of audio signals including a at least one primary audio signal and unwanted signals; and

noise reduction stage configured to receive direction of arrival information of the audio signals and known direction of arrival information representative of at least some of said unwanted signals, the noise reduction stage configured to process the audio signals by treating as noise, portions of the signal identified as unwanted dependent on a comparison between the direction of arrival information of the audio signals and the known direction of arrival information.

18. The user device according to claim 17, wherein the the beamformer is arranged to:

estimate at least one principal direction from which the at least one primary audio signal; and

process the plurality of audio signals to generate a single channel audio output signal by forming a beam in the at least one principal direction and substantially suppressing audio signals from any direction other than the principal direction.

19. The user device according to claim 18, wherein the at least one principal direction is determined by:

determining a time delay that maximizes the cross-correlation between the audio signals being received at the beamformer; and

detecting speech characteristics in the audio signals received at the beamformer with said time delay of maximum cross-correlation.

20. The user device according to claim 17, wherein the noise reduction stage is configured to output audio data received at the user device from the remote node in the communication session.

21. The user device according to claim 17, wherein the unwanted signals are generated by a source at the user device, said source comprising at least one of:

audio output means of the user device;

a source of activity at the user device wherein said activity includes clicking activity comprising button clicking activity, keyboard clicking activity, and mouse clicking activity.

22. The user device according to claim 17, wherein the unwanted signals are generated by a source external to the user device.

23. The user device according to claim 17, wherein the at least one primary audio signal is a speech signal received at the beamformer.

24. A computer program product comprising computer readable instructions stored on a non-transitory computer readable medium for execution by one or more computer processors at a user device for processing a plurality of audio signals including at least one primary audio signal and unwanted signals during a communication session between the user device and a remote node, the instructions comprising instructions for:

receiving direction of arrival information of the audio signals;

providing known direction of arrival information representative of at least some of said unwanted signals; and

processing the audio signals to treat as noise, portions of the signal identified as unwanted dependent on a comparison between the direction of arrival information of the audio signals and the known direction of arrival information.

25. A method of processing audio signals during a communication session between a user device and a remote node, the method comprising:

receiving a plurality of audio signals at the user device including at least one primary audio signal and unwanted signals;

receiving direction of arrival information of the audio signals;

providing known direction of arrival information representative of at least some of said unwanted signals; and

processing the audio signals to treat as noise, portions of the signal identified as unwanted dependent on a comparison between the direction of arrival information of the audio signals and the known direction of arrival information.