Voice enhancement system

• US 20040057586A1
• Filed: 02/13/2003
• Published: 03/25/2004
• Est. Priority Date: 07/27/2000
• Status: Abandoned Application

• Current Assignee: Clear Audio Limited
• Original Assignee: Clear Audio Limited
• Inventors: Licht, Zvi
• Application Number:
  US10/344,599
• Publication Number:
  US 20040057586A1
• Time in Patent Office: Days
• US Class Current: 381/94.7
• CPC Class Codes: H03G 3/32 the control being dependent upon ambient noise level or sound level
• CPC Class Codes: H03G 9/005 of digital or coded signals
• CPC Class Codes: H03G 9/025 frequency-dependent volume compression or expansion, e.g. multiple-band systems H03G9/10, H03G9/18 take precedence
• CPC Class Codes: H04R 3/00 Circuits for transducers , loudspeakers or microphones

Abstract

A method of processing an audio signal in order to overcome background noise extraneous to the audio signal. The method includes comparing a measure of the audio signal in a frequency component of the audio signal to a measure of the noise in a frequency component of the background noise, determining a gain responsive to the comparison and amplifying at least a portion of the audio signal, including at least one frequency segment not included in the frequency component of the audio signal, by the determined gain.

Claims

1. A method of processing an audio signal in order to overcome background noise extraneous to the audio signal, comprising:

comparing a measure of the audio signal in a frequency component of the audio signal to a measure of the noise in a frequency component of the background noise;

determining a gain responsive to the comparison; and

amplifying at least a portion of the audio signal, including at least one frequency segment not included in the frequency component of the audio signal, by the determined gain.

2. A method according to claim 1, wherein the measure of the audio signal comprises a power of the audio signal.

3. A method according to claim 1 or claim 2, wherein the measure of the noise in the frequency component of the background noise comprises a power of a masking version of the noise.

4. A method according to any of the preceding claims, wherein amplifying the at least a portion of the signal comprises amplifying a portion including the compared frequency component of the audio signal.

5. A method according to claim 4, wherein amplifying the at least a portion of the signal comprises amplifying the entire audio signal by the determined gain.

6. A method according to any of the preceding claims, wherein determining the gain to be applied comprises determining a gain which would bring the signal to noise ratio in the frequency band of the frequency component of the audio signal to above a threshold value.

7. A method according to claim 6, wherein the threshold value is dynamically adjusted as the signal and/or noise measure changes in time.

8. A method according to claim 6, wherein the threshold value is a predetermined value.

9. A method according to any of the preceding claims, wherein comparing a measure of the audio signal in a frequency component of the audio signal comprises comparing in a frequency component which includes a formant of the audio signal.

10. A method according to claim 9, wherein comparing in a frequency component which includes a formant of the audio signal comprises comparing in a frequency component of a frequency band with a lowest signal to noise ratio (SNR) among a plurality of frequency components of the audio signal.

11. A method according to any of the preceding claims, comprising dividing the audio signal into a plurality of frequency components and selecting fewer than all the frequency components.

12. A method according to claim 11, wherein selecting fewer than all the frequency components comprises selecting frequency components including formants of the audio signal.

13. A method according to claim 12, wherein selecting frequency components including formants of the audio signal comprises selecting up to a predetermined number of frequency components including formants.

14. A method according to any of claims 11-13, comprising choosing the frequency component of the audio signal, from the selected frequency components.

15. A method according to any of the preceding claims, wherein amplifying the at least a portion of the audio signal comprises amplifying by a gain combined from a plurality of gains including the gain determined responsive to the comparison.

16. A method according to any of the preceding claims, comprising sounding the amplified signal in the presence of the background noise.

17. A method according to any of the preceding claims, wherein the frequency component of the audio signal and the frequency component of the noise span over substantially the same frequency band.

18. A method according to any of the preceding claims, wherein the frequency component of the audio signal comprises a band of frequencies.

19. A method of processing an audio signal in order to overcome background noise extraneous to the audio signal, comprising:

dividing the audio signal into a plurality of frequency components;

enhancing each of the frequency components by a respective noise independent gain of the frequency component; and

multiplying each of the frequency components by a respective noise dependent gain of the frequency component.

20. A method according to claim 19, comprising recombining the plurality of frequency components into an enhanced audio signal.

21. A method according to claim 19 or claim 20, wherein dividing the audio signal into a plurality of frequency components comprises dividing into between 10-24 frequency components.

22. A method according to claim 19 or claim 20, wherein dividing the audio signal into a plurality of frequency components comprises dividing into more than 100 frequency components.

23. A method according to any of claims 19-22, wherein dividing the audio signal into a plurality of frequency components comprises dividing into a plurality of frequency components, which are substantially non-overlapping.

24. A method according to any of claims 19-23, wherein enhancing each of the frequency components by a respective noise independent gain comprises enhancing by predetermined signal-independent gains.

25. A method according to any of claims 19-24, wherein multiplying each of the frequency components by a respective noise dependent gain comprises multiplying substantially all the frequency components by the same noise dependent gain.

26. A method according to any of claims 19-25, wherein the enhancing and multiplying are performed by a single functional element.

27. A method according to any of claims 19-25, wherein the enhancing and multiplying are performed by separate functional elements.

28. A method according to any of claims 19-27, wherein the noise independent gain comprises a voiced speech enhancement factor if the audio signal includes voiced speech.

29. A method according to any of claims 19-28, wherein dividing the audio signal into a plurality of frequency components comprises applying a Fourier transform to the audio signal.

30. A method according to any of claims 19-28, wherein dividing the audio signal into a plurality of frequency components comprises passing the audio signal through an array of band-pass filters.

31. A method of processing an audio signal in order to overcome background noise extraneous to the audio signal, comprising:

receiving an audio signal;

enhancing the audio signal responsive to a measure of the background noise; and

providing an output that is a weighted sum of the enhanced audio signal and the received audio signal.

32. A method according to claim 31, wherein enhancing the audio signal comprises multiplying a plurality of frequency components of the audio signal by respective gains.

33. A method according to claim 31 or 32, wherein providing the weighted slim comprises providing a weighted sum generated by dynamically adjusted weights.

34. A method according to claim 33, wherein the dynamically adjusted weights are determined responsive to the extent to which the audio signal was enhanced.

35. A method according to claim 33 or claim 34, wherein enhancing the audio signal comprises calculating a plurality of different gain factors and multiplying the audio signal by the plurality of gain factors, and wherein the dynamically adjusted weights are determined responsive to one of the gain factors.

36. A method according to claim 35, wherein at least one of the different gain factors comprises a history dependent gain factor.

37. A method according to any of claims 31-36, wherein providing the weighted sum comprises providing a weighted sum generated by predetermined weights.

38. A method according to any of claims 31-37, wherein providing the weighted sum comprises providing a weighted sum in which the received audio signal is dominant, responsive to a determination that a listener to the provided weighted sum is talking.

39. A method according to any of claims 31-37, wherein providing the weighted sum comprises providing a weighted sum in which the received audio signal is dominant, responsive to a determination that the audio signal does not include speech signals.

40. A noise compensation system, comprising:

an input interface adapted to receive an audio signal;

a speaker adapted to sound an enhanced audio signal;

a microphone adapted to collect background noise, that may interfere with a listener listening to the enhanced signal; and

a controller adapted to compare a measure of the audio signal in a frequency component of the audio signal to a measure of the background noise in the same frequency component, determine a gain responsive to the comparison and amplify at least a portion of the audio signal, including at least one segment not in the frequency component, by the determined gain, so as to provide the enhanced audio signal.

41. A system according to claim 40, wherein the speaker and microphone a=e part of a telephone hand-set.

42. A system according to claim 40 or claim 41, comprising an echo canceller which removes at least one echo of the enhanced audio signal from the background noise.

43. A system according to claim 42, wherein the echo canceller removes only a single echo of the enhanced audio signal from the background noise.

44. A method of determining a gain for enhancing an audio signal so as to overcome a background noise extraneous to the audio signal, comprising:

determining a plurality of high-point values over time of a measure of the audio signal;

averaging the high point values;

comparing the average to a measure of the noise; and

determining a gain to enhance the audio signal responsive to the comparison.

45. A method according to claim 44, wherein determining the plurality of high-point values comprises determining high point values for different time segments of the audio signal.

46. A method according to claim 45, wherein determining the plurality of high-point values comprises determining high point values for time segments of the audio signal having different lengths.

47. A method according to any of claims 44-46, wherein determining the plurality of high-point values comprises determining maximal values.

48. A method according to any of claims 44-46, wherein determining the plurality of high-point values comprises determining maximal values of a weighted version of the audio signal, in which more recent values are given higher weight.

49. A method according to any of claims 4448, wherein averaging the high-point values comprises calculating a geometric average.