Adapted audio response

• US 20060262938A1
• Filed: 05/18/2005
• Published: 11/23/2006
• Est. Priority Date: 05/18/2005
• Status: Abandoned Application

• Current Assignee: Bose Corporation
• Original Assignee: Bose Corporation
• Inventors: Johnson, Edwin C. Jr., Hanagami, Nathan, Ickler, Christopher B., Gauger, Daniel M. Jr.
• Application Number:
  US11/131,913
• Publication Number:
  US 20060262938A1
• Time in Patent Office: Days
• US Class Current: 381/56
• 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: H03G 3/32 the control being dependent upon ambient noise level or sound level
• CPC Class Codes: H03G 7/002 in untuned or low-frequency amplifiers, e.g. audio amplifiers H03G7/007, H03G7/001, H03G7/008, H03G7/02, H03G7/06 take precedence

Abstract

Adapting an audio response addresses perceptual effects of an interfering signal, such as of a residual ambient noise or other interference in an earpiece of a headphone. In one aspect, an input audio signal is presented substantially unmodified when it is at levels substantially above the interfering signal and is compressed when at or below the level of the interfering signal. The approach can make use of a measured level of an acoustic signal, for example, within an earpiece of a headset, and use the measured level in conjunction with the level of an input audio signal to determine compression characteristics without requiring separation of an interfering signal present in the monitored acoustic signal from a component related to the input audio signal. In another aspect, presentation characteristics of an input audio signal are determined to reduce distraction from an interfering signal, such as from a background conversation.

Claims

1. A method for processing an audio signal comprising:

receiving the audio signal;

monitoring an acoustic signal that includes components of an interfering signal and the audio signal;

generating a processed audio signal including compressing the audio signal at a first compression ratio when the audio signal is at a first level determined from the monitored acoustic signal and compressing the audio signal at a second compression ratio when the audio signal is above a second level determined from the monitored acoustic signal, the first level being lower than the second level and the first compression ratio being at least three times greater than the second compression ratio.

2. The method of claim 1 wherein generating the processed audio signal further comprises selecting a compression ratio according to a relationship between a level of the audio signal and a level of the acoustic signal.

3. The method of claim 2 further comprising determining the relationship between the level of the audio signal and the level of the acoustic signal without separating the components of the interfering signal and the audio signal.

4. The method 6 f claim 1 wherein generating the processed audio signal comprises reducing a masking effect related to the interfering signal.

5. The method of claim 4 wherein reducing the masking effect related to the interfering signal comprises at least one of reducing an intelligibility of the interfering signal, reducing a distraction by the interfering signal, and partially masking the interfering signal.

6. The method of claim 1 wherein generating the processed audio signal comprises adjusting at least one of a gain and a compression of the audio signal according to a masking effect related to the interfering signal and to the audio signal.

7. The method of claim 1 wherein the second compression ratio is approximately one to one.

8. The method of claim 1 wherein the second compression ratio is less than two to one.

9. The method of claim 1 wherein the first compression ratio is at least three to one.

10. The method of claim 1 wherein the first compression ratio is at least five to one.

11. The method of claim 1 wherein compressing the audio signal further comprises applying the second compression ratio when a level of the audio signal is at least 10 dB above a level of the interfering signal.

12. The method of claim 1 further comprising transmitting the processed audio signal to an earpiece.

13. The method of claim 12 wherein monitoring the acoustic signal comprises monitoring the acoustic signal in the earpiece.

14. The method of claim 12 wherein a source of the interfering signal is outside of the earpiece.

15. The method of claim 1 wherein the acoustic signal includes at least some component of the audio signal.

16. The method of claim 15 wherein monitoring the acoustic signal comprises monitoring the acoustic signal outside an earpiece.

17. The method of claim 1 further comprising applying active noise reduction according to the acoustic signal.

18. The method of claim 1 further comprising determining a time-varying relationship between a level of the audio signal and a level of the acoustic signal.

19. The method of claim 18 wherein generating the processed audio signal comprises varying a gain of the audio signal over time according to the time-varying relationship.

20. The method of claim 18 wherein generating the processed audio signal comprises varying a degree of compression of the audio signal over time according to the time-varying relationship.

21. The method of claim 1 wherein generating the processed audio signal further comprises expanding the audio signal when the audio signal is below a threshold level.

22. An audio processing system comprising:

an input for receiving an audio signal;

a microphone for monitoring an acoustic signal, the acoustic signal including components of an interfering signal and the audio signal;

a compressor circuit for compressing the audio signal at a first compression ratio when the audio signal is at a first level determined from the monitored acoustic signal and compressing the audio signal at a second compression ratio when the audio signal is above a second level determined from the monitored acoustic signal, the first level being lower than the second level and the first compression ratio being at least three times greater than the second compression ratio.

23. The audio processing system of claim 22 wherein the compressor circuit is configured to reduce a masking effect related to the interfering signal.

24. The audio processing system of claim 23 wherein reducing the masking effect related to the interfering signal comprises at least one of reducing an intelligibility of the interfering signal, reducing a distraction by the interfering signal, and partially masking the interfering signal.

25. The audio processing system of claim 23 further comprising a tracking circuit configured to determine a relationship between a level of the audio signal and a level of the acoustic signal without separating the components of the audio signal and the interfering signal.

26. The audio processing system of claim 22 wherein the second level is greater than the first level.

27. The audio processing system of claim 22 wherein the acoustic signal monitored by the microphone includes a at least some component of the audio signal.

28. The audio processing system of claim 22 further comprising an earpiece containing the microphone and a driver.

29. The audio processing system of claim 22 wherein at least one of the tracking circuit and the compressor circuit is at least partially contained within the earpiece.

30. The audio processing system of claim 22 further comprising:

a masking module that receives the audio signal and the acoustic signal, the masking module including circuitry for processing the audio signal according to a level of the acoustic signal, including controlling a level of the audio signal input to reduce a masking effect of an interfering signal present in the acoustic signal.

31. The audio processing system of claim 30 further comprising a selector to selectively enable at least one of the compression circuit and the masking module.

32. A method for audio processing comprising:

receiving an audio signal;

monitoring an acoustic signal that is related to the audio signal;

determining a threshold level according to a relationship between a level of the audio signal and a level of the acoustic signal; and

processing the audio signal by compressing the audio signal when the threshold level is below a first level and maintaining the audio signal substantially unmodified when the threshold level is above a second level.

33. The method of claim 32 wherein processing the audio signal further comprises reducing a masking effect of the interfering signal in response to the threshold level.

34. The method of claim 33 wherein reducing the masking effect comprises at least one of reducing an intelligibility of the interfering signal, reducing a distraction by the interfering signal, and partially masking the interfering signal.

35. The method of claim 33 wherein determining a threshold level comprises determining a relationship between a level of the audio signal and a level of the acoustic signal without separating the components related to the audio signal and an interfering signal.

36. The method of claim 32 wherein determining a threshold level comprises determining according to a relationship between a level of the audio signal and a level of the acoustic signal without separating the components related to the audio signal and an interfering signal.

37. The method of claim 32 wherein compressing the audio signal when the threshold level is below a first level comprises applying a compression ratio that is at least three to one.

38. The method of claim 32 wherein compressing the audio signal when the threshold level is below a first level comprises applying a compression ratio that is at least five to one.

39. The method of claim 32 wherein maintaining the audio signal substantially unmodified comprises passing the audio signal without substantial compression.

40. The method of claim 39 wherein passing the audio signal without substantial compression comprises applying a compression ratio that is approximately one to one.

41. The method of claim 32 wherein the threshold level corresponds to the second level when a level of the audio signal is at least 10 dB above a level of an interfering signal.

42. The method of claim 32 further comprising determining a level of an interfering signal based on a level of the acoustic signal and a level of the audio signal.

43. The method of claim 32 wherein determining the threshold level comprises determining a time-varying relationship between a level of the audio signal and a level of the acoustic signal.

44. The method of claim 32 wherein processing the audio signal further comprises expanding the audio signal when the audio signal is below a threshold level.

45. A method for audio processing comprising:

receiving an audio signal;

monitoring an acoustic signal that includes components related to the audio signal and an interfering signal;

determining a relationship between a level of the audio signal and a level of the acoustic signal without separating the components related to the audio signal and the interfering signal; and

generating a processed audio signal by processing the audio signal according to the relationship to reduce a masking effect of the interfering signal.

46. The method of claim 45 wherein determining the relationship is performed without reconstructing the interfering signal.

47. The method of claim 45 further comprising presenting the processed audio signal in an earpiece.

48. The method of claim 47 wherein monitoring the acoustic signal comprises monitoring the acoustic signal in the earpiece.

49. The method of claim 45 wherein determining the relationship between the audio signal and the acoustic signal comprises determining a relative level of the audio signal and the acoustic signal.

50. The method of claim 45 further comprising applying an active noise reduction approach according to the monitored acoustic signal.

51. The method of claim 45 wherein reducing the masking effect comprises at least one of reducing an intelligibility of the interfering signal, reducing a distraction by the interfering signal, and partially masking the interfering signal.

52. The method of claim 45 wherein determining the relationship between the level of the audio signal and the level of the acoustic signal comprises determining a time-varying relationship.

53. The method of claim 52 wherein generating the processed audio signal comprises varying a gain of the audio signal over time according to the time-varying relationship.

54. The method of claim 52 wherein generating the processed audio signal comprises varying a degree of compression of the audio signal over time according to the time-varying relationship.

55. The method of claim 45 wherein generating the processed audio signal comprises amplifying portions of the audio signal according to a relative level of the audio signal and the acoustic signal.

56. The method of claim 55 wherein amplifying portions of the audio signal comprises applying greater gain to low level portions of the audio signal relative to gain applied to high level portions of the audio signal.

57. The method of claim 45 wherein the processed audio signal is substantially the same as the audio signal when the audio signal is above a threshold level.

58. The method of claim 45 wherein generating the processed audio signal comprises expanding the audio signal when the audio signal is below a threshold level.

59. A masking module comprising:

a first input for receiving an audio signal;

a second input for receiving a microphone signal that includes components related to the audio signal and an interfering signal; and

a correlator for processing the audio signal according to a level of the microphone signal and a level of a modified audio signal, a level of the modified audio signal being controlled to reduce a masking effect of the interfering signal.

60. The masking module of claim 59 further comprising a control circuit that controls the level of the modified audio signal.

61. The masking according to claim 60 wherein the control circuit controls the level of the modified audio signal such that an output of the correlator is substantially equal to a threshold value.

62. The masking module of claim 60 wherein the control circuit comprises an integrator, an output of the integrator being responsive to an output of the correlator and an output of a user controllable correlation target.

63. The masking module of claim 59 further comprising a bandpass filter that filters the microphone signal and a bandpass filter that filters the modified audio signal.