Systems, methods, and apparatus for multichannel signal amplitude balancing

• US 8,321,214 B2
• Filed: 05/28/2009
• Issued: 11/27/2012
• Est. Priority Date: 06/02/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chan, Kwokleung, Park, Hyun Jin
• Primary Examiner(s): MCFADDEN, SUSAN IRIS
• Application Number:
  US12/473,930
• Publication Number:
  US 20090299739A1
• Time in Patent Office: 1,279 Days
• Field of Search: 704/225
• US Class Current: 704/225
• CPC Class Codes: G10L 2021/02166 Microphone arrays; Beamforming
• 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 processing a multichannel audio signal may be configured to control the amplitude of one channel of the signal relative to another based on the levels of the two channels. One such example uses a bias factor, which is based on a standard orientation of an audio sensing device relative to a directional acoustic information source, for amplitude control of information segments of the signal.

Claims

1. A method of processing, on a processor, a multichannel audio signal, said method comprising:

calculating a series of values of a level of a first channel of the audio signal over time;

calculating a series of values of a level of a second channel of the audio signal over time;

based on the series of values of a level of the first channel and the series of values of a level of the second channel, calculating a series of values of a gain factor over time; and

controlling the amplitude of the second channel relative to the amplitude of the first channel over time according to the series of values of the gain factor,

wherein said method includes indicating that a segment of the audio signal is an information segment, and

wherein calculating a series of values of a gain factor over time includes, for at least one of the series of values of the gain factor and in response to said indicating, calculating the gain factor value based on a corresponding value of the level of the first channel, a corresponding value of the level of the second channel, and a bias factor, and

wherein the bias factor is based on a standard orientation of an audio sensing device relative to a directional information source.

2. The method of processing a multichannel audio signal according to claim 1, wherein said indicating that a segment is an information segment is based on a corresponding value of the level of the first channel and a corresponding value of the level of the second channel.

3. The method of processing a multichannel audio signal according to claim 1, wherein said indicating that a segment is an information segment is based on a relation that includes an array imbalance estimate, and

wherein the array imbalance estimate is based on at least one of the series of values of the gain factor.

4. The method of processing a multichannel audio signal according to claim 1, wherein each of the series of values of a gain factor is based on a ratio of one of the series of values of a level of the first channel to one of the series of values of a level of the second channel.

5. The method of processing a multichannel audio signal according to claim 1, wherein the bias factor is independent of a ratio between the corresponding value of the level of the first channel and the corresponding value of the level of the second channel.

6. The method of processing a multichannel audio signal according to claim 1, wherein said calculating the gain factor value includes using the bias factor to weight the corresponding value of the level of the second channel, and

wherein said gain factor value is based on a ratio of the corresponding value of the level of the first channel to the weighted corresponding value of the level of the second channel.

7. The method of processing a multichannel audio signal according to claim 1, wherein said method includes indicating that a segment of the audio signal is a background segment, based on a relation between a level of the segment and a background level value.

8. The method of processing a multichannel audio signal according to claim 1, wherein said method includes indicating that a segment of the audio signal which is not a background segment is a balanced noise segment.

9. The method of processing a multichannel audio signal according to claim 1, wherein said method includes indicating that a segment of the audio signal which is not a background segment is a balanced noise segment, based on a relation that includes an array imbalance estimate, and

wherein the array imbalance estimate is based on at least one of the series of values of the gain factor.

10. A non-transitory computer-readable medium comprising instructions which when executed by at least one processor cause the at least one processor to perform a method of processing a multichannel audio signal, said instructions comprising:

instructions which when executed by a processor cause the processor to calculate a series of values of a level of a first channel of the audio signal over time;

instructions which when executed by a processor cause the processor to calculate a series of values of a level of a second channel of the audio signal over time;

instructions which when executed by a processor cause the processor to calculating a series of values of a gain factor over time, based on the series of values of a level of the first channel and the series of values of a level of the second channel; and

instructions which when executed by a processor cause the processor to control the amplitude of the second channel relative to the amplitude of the first channel over time according to the series of values of the gain factor,

wherein said medium includes instructions which when executed by a processor cause the processor to indicate that a segment of the audio signal is an information segment, and

wherein said instructions which when executed by a processor cause the processor to calculate a series of values of a gain factor over time include instructions which when executed by a processor cause the processor to calculate at least one of the series of values of the gain factor, in response to the indication, based on a corresponding value of the level of the first channel, a corresponding value of the level of the second channel, and a bias factor, and

wherein the bias factor is based on a standard orientation of an audio sensing device relative to a directional information source.

11. The computer-readable medium according to claim 10, wherein said instructions which when executed by a processor cause the processor to indicate that a segment is an information segment include instructions which when executed by a processor cause the processor to indicate that a segment is an information segment based on a corresponding value of the level of the first channel and a corresponding value of the level of the second channel.

12. The computer-readable medium according to claim 10, wherein said instructions which when executed by a processor cause the processor to indicate that a segment is an information segment include instructions which when executed by a processor cause the processor to indicate that a segment is an information segment based on a relation that includes an array imbalance estimate, and

wherein the array imbalance estimate is based on at least one of the series of values of the gain factor.

13. The computer-readable medium according to claim 10, wherein each of the series of values of a gain factor is based on a ratio of one of the series of values of a level of the first channel to one of the series of values of a level of the second channel.

14. The computer-readable medium according to claim 10, wherein the bias factor is independent of a ratio between the corresponding value of the level of the first channel and the corresponding value of the level of the second channel.

15. The computer-readable medium according to claim 10, wherein said instructions which when executed by a processor cause the processor to calculate the gain factor value include instructions which when executed by a processor cause the processor to use the bias factor to weight the corresponding value of the level of the second channel, and

wherein said gain factor value is based on a ratio of the corresponding value of the level of the first channel to the weighted corresponding value of the level of the second channel.

16. The computer-readable medium according to claim 10, wherein said medium includes instructions which when executed by a processor cause the processor to indicate that a segment of the audio signal is a background segment, based on a relation between a level of the segment and a background level value.

17. The computer-readable medium according to claim 10, wherein said medium includes instructions which when executed by a processor cause the processor to indicate that a segment of the audio signal which is not a background segment is a balanced noise segment.

18. The computer-readable medium according to claim 10, wherein said medium includes instructions which when executed by a processor cause the processor to indicate that a segment of the audio signal which is not a background segment is a balanced noise segment, based on a relation that includes an array imbalance estimate, and

wherein the array imbalance estimate is based on at least one of the series of values of the gain factor.

19. An apparatus for processing a multichannel audio signal, said apparatus comprising:

means for calculating a series of values of a level of a first channel of the audio signal over time;

means for calculating a series of values of a level of a second channel of the audio signal over time;

means for calculating a series of values of a gain factor over time, based on the series of values of a level of the first channel and the series of values of a level of the second channel; and

means for controlling the amplitude of the second channel relative to the amplitude of the first channel over time according to the series of values of the gain factor,

wherein said apparatus includes means for indicating that a segment of the audio signal is an information segment, and

wherein said means for calculating a series of values of a gain factor over time is configured to calculate at least one of the series of values of the gain factor, in response to the indication, based on a corresponding value of the level of the first channel, a corresponding value of the level of the second channel, and a bias factor, and

wherein the bias factor is based on a standard orientation of an audio sensing device relative to a directional information source.

20. The apparatus for processing a multichannel audio signal according to claim 19, wherein said means for indicating that a segment is an information segment is configured to indicate that a segment is an information segment based on a corresponding value of the level of the first channel and a corresponding value of the level of the second channel.

21. The apparatus for processing a multichannel audio signal according to claim 19, wherein said means for indicating that a segment is an information segment is configured to indicate that a segment is an information segment based on a relation that includes an array imbalance estimate, and

wherein the array imbalance estimate is based on at least one of the series of values of the gain factor.

22. The apparatus for processing a multichannel audio signal according to claim 19, wherein each of the series of values of a gain factor is based on a ratio of one of the series of values of a level of the first channel to one of the series of values of a level of the second channel.

23. The apparatus for processing a multichannel audio signal according to claim 19, wherein the bias factor is independent of a ratio between the corresponding value of the level of the first channel and the corresponding value of the level of the second channel.

24. The apparatus for processing a multichannel audio signal according to claim 19, wherein said means for calculating the gain factor value is configured to calculate each of the at least one of the series of values of the gain factor using the bias factor to weight the corresponding value of the level of the second channel, and

wherein said gain factor value is based on a ratio of the corresponding value of the level of the first channel to the weighted corresponding value of the level of the second channel.

25. The apparatus for processing a multichannel audio signal according to claim 19, wherein said apparatus includes means for indicating that a segment of the audio signal is a background segment, based on a relation between a level of the segment and a background level value.

26. The apparatus for processing a multichannel audio signal according to claim 19, wherein said apparatus includes means for indicating that a segment of the audio signal which is not a background segment is a balanced noise segment.

27. The apparatus for processing a multichannel audio signal according to claim 19, wherein said apparatus includes means for indicating that a segment of the audio signal which is not a background segment is a balanced noise segment, based on a relation that includes an array imbalance estimate, and

wherein the array imbalance estimate is based on at least one of the series of values of the gain factor.

28. The apparatus for processing a multichannel audio signal according to claim 19, wherein said apparatus comprises a communications device that includes said means for calculating a series of values of a level of a first channel, said means for calculating a series of values of a level of a second channel, said means for calculating a series of values of a gain factor, said means for controlling the amplitude of the second channel, and said means for indicating that a segment of the audio signal is an information segment, and

wherein the communications device comprises a microphone array configured to produce the multichannel audio signal.

29. An apparatus for processing a multichannel audio signal, said apparatus comprising:

a first level calculator configured to calculate a series of values of a level of a first channel of the audio signal over time;

a second level calculator configured to calculate a series of values of a level of a second channel of the audio signal over time;

a gain factor calculator configured to calculate a series of values of a gain factor over time, based on the series of values of a level of the first channel and the series of values of a level of the second channel;

an amplitude control element configured to control the amplitude of the second channel relative to the amplitude of the first channel over time according to the series of values of the gain factor; and

an information segment indicator configured to indicate that a segment of the audio signal is an information segment,

wherein said gain factor calculator is configured to calculate at least one of the series of values of the gain factor, in response to the indication, based on a corresponding value of the level of the first channel, a corresponding value of the level of the second channel, and a bias factor, and

wherein the bias factor is based on a standard orientation of an audio sensing device relative to a directional acoustic information source.

30. The apparatus for processing a multichannel audio signal according to claim 29, wherein said information segment indicator is configured to indicate that a segment is an information segment based on a corresponding value of the level of the first channel and a corresponding value of the level of the second channel.

31. The apparatus for processing a multichannel audio signal according to claim 29, wherein said information segment indicator is configured to indicate that a segment is an information segment based on a relation that includes an array imbalance estimate, and

wherein the array imbalance estimate is based on at least one of the series of values of the gain factor.

32. The apparatus for processing a multichannel audio signal according to claim 29, wherein each of the series of values of a gain factor is based on a ratio of one of the series of values of a level of the first channel to one of the series of values of a level of the second channel.

33. The apparatus for processing a multichannel audio signal according to claim 29, wherein the bias factor is independent of a ratio between the corresponding value of the level of the first channel and the corresponding value of the level of the second channel.

34. The apparatus for processing a multichannel audio signal according to claim 29, wherein said gain factor calculator is configured to calculate each of the at least one of the series of values of the gain factor using the bias factor to weight the corresponding value of the level of the second channel, and

wherein said gain factor value is based on a ratio of the corresponding value of the level of the first channel to the weighted corresponding value of the level of the second channel.

35. The apparatus for processing a multichannel audio signal according to claim 29, wherein said apparatus includes a background segment indicator configured to indicate that a segment of the audio signal is a background segment, based on a relation between a level of the segment and a background level value.

36. The apparatus for processing a multichannel audio signal according to claim 29, wherein said apparatus includes a balanced noise segment indicator configured to indicate that a segment of the audio signal which is not a background segment is a balanced noise segment.

37. The apparatus for processing a multichannel audio signal according to claim 29, wherein said apparatus includes a balanced noise segment indicator configured to indicate that a segment of the audio signal which is not a background segment is a balanced noise segment, based on a relation that includes an array imbalance estimate, and

wherein the array imbalance estimate is based on at least one of the series of values of the gain factor.

38. The apparatus for processing a multichannel audio signal according to claim 29, wherein said apparatus comprises a communications device that includes said first level calculator, said second level calculator, said gain factor calculator, said amplitude control element, and said information segment indicator, and

wherein the communications device comprises a microphone array configured to produce the multichannel audio signal.