SYSTEMS, METHODS, APPARATUS, AND COMPUTER-READABLE MEDIA FOR ADAPTIVE ACTIVE NOISE CANCELLATION

• US 20110007907A1
• Filed: 07/09/2010
• Published: 01/13/2011
• Est. Priority Date: 07/10/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Li, Ren, Park, Hyun Jin, CHAN, Kwokeung
• Granted Patent: US 8,737,636 B2
• Time in Patent Office: Days
• US Class Current: 381/71.8
• CPC Class Codes: G10K 11/002 Devices for damping, suppressing, obstructing or conducting sound in acoustic devices G10K1/06 - G10K1/10 take precedence; for electro-mechanical transducers for communication H04R3/002
• CPC Class Codes: G10K 11/17817 between the output signals and the error signals, i.e. secondary path
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17855 for improving speed or power requirements
• CPC Class Codes: G10K 11/17857 Geometric disposition, e.g. placement of microphones
• CPC Class Codes: G10K 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone
• CPC Class Codes: G10K 11/17885 additionally using a desired external signal, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 2210/108 Communication systems, e.g. where useful sound is kept and noise is cancelled
• CPC Class Codes: G10K 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets
• CPC Class Codes: G10K 2210/3028 Filtering, e.g. Kalman filters or special analogue or digital filters

Abstract

An adaptive active noise cancellation apparatus performs a filtering operation in a first digital domain and performs adaptation of the filtering operation in a second digital domain.

Claims

1. A method of producing an antinoise signal, said method comprising:

producing the antinoise signal during a first time interval by applying a digital filter to a reference noise signal in a filtering domain having a first sampling rate; and

producing the antinoise signal during a second time interval subsequent to the first time interval by applying the digital filter to the reference noise signal in the filtering domain, wherein during said first time interval, the digital filter has a first filter state, and wherein during the second time interval, the digital filter has a second filter state different than the first filter state, and

wherein said method includes, in an adaptation domain having a second sampling rate that is lower than the first sampling rate, calculating the second filter state based on information from the reference noise signal and information from an error signal.

2. The method of producing an antinoise signal according to claim 1, wherein said digital filter includes:

a feedback filter configured to filter the antinoise signal to produce a feedback signal; and

a feedforward filter configured to filter a sum of the reference noise signal and the feedback signal to produce the antinoise signal.

3. The method of producing an antinoise signal according to claim 2, wherein said calculating the second filter state includes updating at least one feedforward coefficient of the feedforward filter and at least one feedforward coefficient of the feedback filter.

4. The method of producing an antinoise signal according to claim 2, wherein each of said feedforward filter and said feedback filter is an infinite-impulse-response filter.

5. The method of producing an antinoise signal according to claim 1, wherein said first filter state includes a filter gain, and wherein said calculating the second filter state includes calculating an update for said filter gain.

6. The method of producing an antinoise signal according to claim 1, wherein the first sampling rate is at least fifty thousand Hertz.

7. The method of producing an antinoise signal according to claim 1, wherein the first sampling rate is at least eight times the second sampling rate.

8. The method of producing an antinoise signal according to claim 1, wherein the first sampling rate is at least sixty-four times the second sampling rate.

9. The method of producing an antinoise signal according to claim 1, wherein said method includes calculating an estimate of an acoustic path, based on a desired sound signal, and wherein said second filter state is based on the calculated acoustic path estimate.

10. The method of producing an antinoise signal according to claim 1, wherein said method includes receiving a sensed noise signal from each of a plurality of different microphones, and

wherein the reference noise signal is based on information from each of the plurality of sensed noise signals.

11. The method of producing an antinoise signal according to claim 1, wherein said producing the antinoise signal during a first time interval includes producing the antinoise signal by summing a result of said applying a digital filter to a reference noise signal during the first time interval with a result of applying a second digital filter to the error signal in the filtering domain during the first time interval, and

wherein said producing the antinoise signal during a second time interval includes producing the antinoise signal by summing a result of said applying a digital filter to a reference noise signal during the second time interval with a result of applying a second digital filter to the error signal in the filtering domain during the second time interval, and

wherein during said first time interval, the second digital filter has a third filter state, and wherein during the second time interval, the second digital filter has a fourth filter state different than the third filter state, and

wherein said method includes, in the adaptation domain, calculating the fourth filter state based on information from the error signal.

12. An apparatus for producing an antinoise signal, said apparatus comprising:

means for producing the antinoise signal during a first time interval by filtering a reference noise signal, according to a first filter state, in a filtering domain having a first sampling rate; and

means for calculating, in an adaptation domain having a second sampling rate that is lower than the first sampling rate, a second filter state based on information from the reference noise signal and information from an error signal, wherein the second filter state is different than the first filter state,

wherein said means for producing the antinoise signal is configured to produce the antinoise signal during a second time interval subsequent to the first time interval by filtering the reference noise signal in the filtering domain according to the second filter state.

13. The apparatus for producing an antinoise signal according to claim 12, wherein said means for producing the antinoise signal includes:

means for filtering the antinoise signal to produce a feedback signal; and

means for filtering a sum of the reference noise signal and the feedback signal to produce the antinoise signal.

14. The apparatus for producing an antinoise signal according to claim 13, wherein said means for calculating the second filter state is configured to update at least one feedforward coefficient of said means for filtering the antinoise signal to produce a feedback signal and at least one feedforward coefficient of said means for filtering a sum of the reference noise signal and the feedback signal.

15. The apparatus for producing an antinoise signal according to claim 13, wherein each of said means for filtering the antinoise signal to produce a feedback signal and said means for filtering a sum of the reference noise signal and the feedback signal is an infinite-impulse-response filter.

16. The apparatus for producing an antinoise signal according to claim 12, wherein said first filter state includes a filter gain, and wherein said calculating the second filter state includes calculating an update for said filter gain.

17. The apparatus for producing an antinoise signal according to claim 12, wherein the first sampling rate is at least fifty thousand Hertz.

18. The apparatus for producing an antinoise signal according to claim 12, wherein the first sampling rate is at least eight times the second sampling rate.

19. The apparatus for producing an antinoise signal according to claim 12, wherein the first sampling rate is at least sixty-four times the second sampling rate.

20. The apparatus for producing an antinoise signal according to claim 12, wherein said apparatus includes means for calculating an estimate of an acoustic path, based on a desired sound signal, and wherein said second filter state is based on the calculated acoustic path estimate.

21. The apparatus for producing an antinoise signal according to claim 12, wherein said apparatus includes means for producing the reference noise signal, wherein said means is configured to receive a sensed noise signal from each of a plurality of different microphones, and

wherein the reference noise signal is based on information from each of the plurality of sensed noise signals.

22. The apparatus for producing an antinoise signal according to claim 12, wherein said means for producing the antinoise signal is configured to produce the antinoise signal during a first time interval by summing a result of said applying a digital filter to a reference noise signal during the first time interval with a result of applying a second digital filter to the error signal in the filtering domain during the first time interval, and wherein said means for producing the antinoise signal is configured to produce the antinoise signal during a second time interval by summing a result of said applying a digital filter to a reference noise signal during the second time interval with a result of applying a second digital filter to the error signal in the filtering domain during the second time interval, and

wherein during said first time interval, the second digital filter has a third filter state, and wherein during the second time interval, the second digital filter has a fourth filter state different than the third filter state, and

wherein said means for calculating is configured to calculate, in the adaptation domain, the fourth filter state based on information from the error signal.

23. An apparatus for producing an antinoise signal, said apparatus comprising:

a digital filter configured to produce the antinoise signal during a first time interval by filtering a reference noise signal, according to a first filter state, in a filtering domain having a first sampling rate; and

a control block configured to calculate, in an adaptation domain having a second sampling rate that is lower than the first sampling rate, a second filter state based on information from the reference noise signal and information from an error signal,

wherein the second filter state is different than the first filter state, wherein the digital filter is configured to produce the antinoise signal during a second time interval subsequent to the first time interval by filtering the reference noise signal in the filtering domain according to the second filter state.

24. The apparatus for producing an antinoise signal according to claim 23, wherein said digital filter includes:

a feedback filter configured to filter the antinoise signal to produce a feedback signal; and

a feedforward filter configured to filter a sum of the reference noise signal and the feedback signal to produce the antinoise signal.

25. The apparatus for producing an antinoise signal according to claim 24, wherein said control block is configured to update at least one feedforward coefficient of the feedforward filter and at least one feedforward coefficient of the feedback filter.

26. The apparatus for producing an antinoise signal according to claim 24, wherein each of said feedforward filter and said feedback filter is an infinite-impulse-response filter.

27. The apparatus for producing an antinoise signal according to claim 23, wherein said first filter state includes a filter gain, and wherein said calculating the second filter state includes calculating an update for said filter gain.

28. The apparatus for producing an antinoise signal according to claim 23, wherein the first sampling rate is at least fifty thousand Hertz.

29. The apparatus for producing an antinoise signal according to claim 23, wherein the first sampling rate is at least eight times the second sampling rate.

30. The apparatus for producing an antinoise signal according to claim 23, wherein the first sampling rate is at least sixty-four times the second sampling rate.

31. The apparatus for producing an antinoise signal according to claim 23, wherein said control block is configured to calculate an estimate of an acoustic path, based on a desired sound signal, and wherein said second filter state is based on the calculated acoustic path estimate.

32. The apparatus for producing an antinoise signal according to claim 23, wherein said apparatus includes a filter configured to perform a spatially selective processing operation to produce the reference noise signal, wherein said filter is configured to receive a sensed noise signal from each of a plurality of different microphones, and

wherein the reference noise signal is based on information from each of the plurality of sensed noise signals.

33. The apparatus for producing an antinoise signal according to claim 23, wherein said digital filter is configured to filter the error signal, according to a third filter state, in the filtering domain during the first time interval, and

wherein said digital filter is configured to produce the antinoise signal during the first time interval by summing a result of said filtering a reference noise signal during the first time interval with a result of said filtering the error signal during the first time interval, and

wherein said digital filter is configured to filter the error signal, according to a fourth filter state that is different than the third filter state, in the filtering domain during the second time interval, and

wherein said digital filter is configured to produce the antinoise signal during the second time interval by summing a result of said filtering a reference noise signal during the second time interval with a result of said filtering the error signal during the second time interval, and

wherein said apparatus includes a second control block configured to calculate, in the adaptation domain, the fourth filter state based on information from the error signal.

34. An apparatus for producing an antinoise signal, said apparatus comprising:

an integrated circuit configured to produce the antinoise signal during a first time interval by filtering a reference noise signal, according to a first filter state, in a filtering domain having a first sampling rate; and

a computer-readable medium having tangible structures that store machine-executable instructions which when executed by at least one processor cause the at least one processor to calculate, in an adaptation domain having a second sampling rate that is lower than the first sampling rate, a second filter state based on information from the reference noise signal and information from an error signal, wherein the second filter state is different than the first filter state,

wherein the integrated circuit is configured to produce the antinoise signal during a second time interval subsequent to the first time interval by filtering the reference noise signal in the filtering domain according to the second filter state.

35. The apparatus for producing an antinoise signal according to claim 34, wherein said integrated circuit includes:

a feedback filter configured to filter the antinoise signal to produce a feedback signal; and

a feedforward filter configured to filter a sum of the reference noise signal and the feedback signal to produce the antinoise signal.

36. The apparatus for producing an antinoise signal according to claim 35, wherein said instructions include instructions which when executed by at least one processor cause the at least one processor to update at least one feedforward coefficient of the feedforward filter and at least one feedforward coefficient of the feedback filter.

37. The apparatus for producing an antinoise signal according to claim 35, wherein each of said feedforward filter and said feedback filter is an infinite-impulse-response filter.

38. The apparatus for producing an antinoise signal according to claim 34, wherein said first filter state includes a filter gain, and wherein said instructions which when executed by at least one processor cause the at least one processor to calculate the second filter state include instructions to calculate an update for said filter gain.

39. The apparatus for producing an antinoise signal according to claim 34, wherein the first sampling rate is at least fifty thousand Hertz.

40. The apparatus for producing an antinoise signal according to claim 34, wherein the first sampling rate is at least eight times the second sampling rate.

41. The apparatus for producing an antinoise signal according to claim 34, wherein the first sampling rate is at least sixty-four times the second sampling rate.

42. The apparatus for producing an antinoise signal according to claim 34, wherein said instructions include instructions which when executed by at least one processor cause the at least one processor to calculate an estimate of an acoustic path, based on a desired sound signal, and wherein said second filter state is based on the calculated acoustic path estimate.

43. The apparatus of producing an antinoise signal according to claim 34, wherein said apparatus includes a filter configured to perform a spatially selective processing operation to produce the reference noise signal, wherein said filter is configured to receive a sensed noise signal from each of a plurality of different microphones, and wherein the reference noise signal is based on information from each of the plurality of sensed noise signals.

44. The apparatus for producing an antinoise signal according to claim 34, wherein said integrated circuit is configured to filter the error signal, according to a third filter state, in the filtering domain during the first time interval, and

wherein said integrated circuit is configured to produce the antinoise signal during the first time interval by summing a result of said filtering a reference noise signal during the first time interval with a result of said filtering the error signal during the first time interval, and

wherein said integrated circuit is configured to filter the error signal, according to a fourth filter state that is different than the third filter state, in the filtering domain during the second time interval, and

wherein said integrated circuit is configured to produce the antinoise signal during the second time interval by summing a result of said filtering a reference noise signal during the second time interval with a result of said filtering the error signal during the second time interval, and

wherein said instructions include instructions which when executed by at least one processor cause the at least one processor to calculate, in the adaptation domain, the fourth filter state based on information from the error signal.