SYSTEMS AND METHODS FOR DETECTING WIND NOISE USING MULTIPLE AUDIO SOURCES

• US 20090238369A1
• Filed: 11/25/2008
• Published: 09/24/2009
• Est. Priority Date: 03/18/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wang, Song, Ramakrishnan, Dinesh
• Granted Patent: US 8,184,816 B2
• Time in Patent Office: Days
• US Class Current: 381/56
• CPC Class Codes: H04R 2410/07 Mechanical or electrical reduction of wind noise generated by wind passing a 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

A method for detecting wind noise is described. At least two audio signals are received. The at least two audio signals are filtered to reduce higher frequencies and to reduce lower frequencies to provide at least two filtered audio signals. The cross correlation of the at least two filtered audio signals is computed for multiple delays. A maximum cross correlation is determined from the cross correlations computed for the multiple delays. Wind noise is detected by comparing the maximum cross correlation with a threshold.

Claims

1. A method for detecting wind noise, the method comprising:

receiving at least two audio signals;

filtering the at least two audio signals to reduce higher frequencies and to reduce lower frequencies to provide at least two filtered audio signals;

computing the cross correlation of the at least two filtered audio signals for multiple delays;

determining a maximum cross correlation from the cross correlations computed for the multiple delays; and

detecting wind noise by comparing the maximum cross correlation with a threshold.

2. The method of claim 1, wherein the filtering to reduce the higher frequencies is accomplished by a low pass filter.

3. The method of claim 1, wherein the filtering to reduce the lower frequencies is accomplished by a high pass filter.

4. The method of claim 1, wherein the filtering to reduce the higher frequencies and to reduce the lower frequencies is accomplished by a band pass filter.

5. The method of claim 1, wherein computing the cross correlation comprises computing the normalized cross correlation.

6. The method of claim 1, further comprising converting the at least two audio signals from analog audio to digital audio.

7. The method of claim 1, wherein the at least two audio signals comprise exactly two audio signals.

8. The method of claim 1, further comprising:

converting the at least two audio signals from analog audio to digital audio;

dividing the digital audio into multiple blocks; and

wherein the computing, the determining and the detecting are performed relative to the blocks.

9. The method of claim 1, wherein computing the cross correlation comprises computing the smoothed normalized cross correlation.

10. The method of claim 9, further comprising monitoring a percentage of wind noise detections over a window and comparing the percentage with a threshold percentage to determine wind noise for the window.

11. The method of claim 1, further comprising determining which audio signal of the at least two audio signals has wind noise.

12. A wireless communication device configured to detect wind noise, the device comprising:

at least two microphones for receiving at least two audio signals;

filters for filtering the at least two audio signals to reduce higher frequencies and to reduce lower frequencies to provide at least two filtered audio signals;

a cross correlation block coupled to the filters for computing the cross correlation of the at least two filtered audio signals for multiple delays;

a maximum determination block coupled to the cross correlation block for determining a maximum cross correlation from the cross correlations computed for the multiple delays; and

a decision block coupled to the maximum determination block for detecting wind noise by comparing the maximum cross correlation with a threshold.

13. The communication device of claim 12, wherein the filters include a low pass filter to reduce the higher frequencies.

14. The communication device of claim 12, wherein the filters include a high pass filter to reduce the lower frequencies.

15. The communication device of claim 12, wherein the filters include a band pass filter to reduce the higher frequencies and to reduce the lower frequencies.

16. The communication device of claim 12, wherein the cross correlation block is configured to compute the cross correlation by computing the normalized cross correlation.

17. The communication device of claim 12, further comprising analog to digital converters for converting the at least two audio signals from analog audio to digital audio.

18. The communication device of claim 12, wherein the at least two microphones comprise exactly two microphones.

19. The communication device of claim 12, further comprising:

analog to digital converters for converting the at least two audio signals from analog audio to digital audio;

a processor for dividing the digital audio into multiple blocks; and

wherein the cross correlation block, the maximum determination block and the decision block are performed relative to the blocks.

20. The communication device of claim 12, wherein the cross correlation block is configured to compute the cross correlation by computing the smoothed normalized cross correlation.

21. The communication device of claim 20, wherein the processor is further configured to monitor a percentage of wind noise detections over a window and compare the percentage with a threshold percentage to determine wind noise for the window.

22. The communication device of claim 12, further comprising a processor configured to determine which audio signal of the at least two audio signals has wind noise.

23. A wireless communication device configured for detecting wind noise, comprising:

a processor;

memory in electronic communication with the processor;

instructions stored in the memory, the instructions being executable by the processor to;

receive at least two audio signals;

filter the at least two audio signals to reduce higher frequencies and to reduce lower frequencies to provide at least two filtered audio signals;

compute the cross correlation of the at least two filtered audio signals for multiple delays;

determine a maximum cross correlation from the cross correlations computed for the multiple delays; and

detect wind noise by comparing the maximum cross correlation with a threshold.

24. The wireless communication device of claim 23, wherein the instructions are further executable to implement a low pass filter to reduce the higher frequencies.

25. The wireless communication device of claim 23, wherein the instructions are further executable to implement a high pass filter to reduce the lower frequencies.

26. The wireless communication device of claim 23, wherein the instructions are further executable to implement a band pass filter reduce the higher frequencies and to reduce the lower frequencies.

27. The wireless communication device of claim 23, wherein the instructions are further executable to compute the cross correlation by computing the normalized cross correlation.

28. The wireless communication device of claim 23, wherein the instructions are further executable to convert the at least two audio signals from analog audio to digital audio.

29. The wireless communication device of claim 23, wherein the at least two audio signals comprise exactly two audio signals.

30. The wireless communication device of claim 23, further comprising:

executable instructions to convert the at least two audio signals from analog audio to digital audio;

executable instructions to divide the digital audio into multiple blocks; and

wherein the instructions for computing, the instructions for determining and the instructions for detecting are performed relative to the blocks.

31. The wireless communication device of claim 23, wherein the instructions are further executable to compute the cross correlation by computing the smoothed normalized cross correlation.

32. The wireless communication device of claim 31, wherein the instructions are further executable to monitor a percentage of wind noise detections over a window and to compare the percentage with a threshold percentage to determine wind noise for the window.

33. The wireless communication device of claim 23, wherein the instructions are further executable to determine which audio signal of the at least two audio signals has wind noise.

34. A wireless communication device configured for detecting wind noise, comprising:

means for receiving at least two audio signals;

means for filtering the at least two audio signals to reduce higher frequencies and to reduce lower frequencies to provide at least two filtered audio signals;

means for computing the cross correlation of the at least two filtered audio signals for multiple delays;

means for determining a maximum cross correlation from the cross correlations computed for the multiple delays; and

means for detecting wind noise by comparing the maximum cross correlation with a threshold.

35. The method of claim 34, wherein the means for computing the cross correlation comprises means for computing the normalized cross correlation.

36. The method of claim 34, further comprising means for converting the at least two audio signals from analog audio to digital audio.

37. The method of claim 34, wherein the at least two audio signals comprise exactly two audio signals.

38. The method of claim 34, further comprising:

means for converting the at least two audio signals from analog audio to digital audio;

means for dividing the digital audio into multiple blocks; and

wherein the means for computing, the means for determining and the means for detecting are performed relative to the blocks.

39. A computer-program product for detecting wind noise, the computer-program product comprising a computer-readable medium having instructions thereon, the instructions comprising:

code for receiving at least two audio signals;

code for filtering the at least two audio signals to reduce higher frequencies and to reduce lower frequencies to provide at least two filtered audio signals;

code for computing the cross correlation of the at least two filtered audio signals for multiple delays;

code for determining a maximum cross correlation from the cross correlations computed for the multiple delays; and

code for detecting wind noise by comparing the maximum cross correlation with a threshold.

40. The computer-program product of claim 39, wherein the code for computing the cross correlation comprises code for computing the normalized cross correlation.

41. The computer-program product of claim 39, wherein the instructions further comprising code for converting the at least two audio signals from analog audio to digital audio.

42. The computer-program product of claim 39, wherein the at least two audio signals comprise exactly two audio signals.

43. The computer-program product of claim 39, further comprising:

code for converting the at least two audio signals from analog audio to digital audio;

code for dividing the digital audio into multiple blocks; and

wherein the code for computing, the code for determining and the code for detecting are performed relative to the blocks.

44. An integrated circuit for detecting wind noise, the integrated circuit being configured to:

receive at least two audio signals;

filter the at least two audio signals to reduce higher frequencies and to reduce lower frequencies to provide at least two filtered audio signals;

compute the cross correlation of the at least two filtered audio signals for multiple delays;

determine a maximum cross correlation from the cross correlations computed for the multiple delays; and

detect wind noise by comparing the maximum cross correlation with a threshold.

45. The integrated circuit of claim 44, wherein the integrated circuit is further configured to compute the cross correlation by computing the normalized cross correlation.