Signal processing method and apparatus

• US 20070071253A1
• Filed: 08/31/2004
• Published: 03/29/2007
• Est. Priority Date: 09/02/2003
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Sugiyama, Akihiko, Sato, Miki
• Granted Patent: US 7,720,233 B2
• Time in Patent Office: Days
• US Class Current: 381/94.300
• CPC Class Codes: G10L 2021/02165 Two microphones, one receiving mainly the noise signal and the other one mainly the speech signal
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: H03H 2021/0078 varying the step size
• CPC Class Codes: H03H 21/0012 Digital adaptive filters

Abstract

A signal processor includes: a first adaptive filter that takes a first signal as input and generates a first pseudo signal; a first subtractor that subtracts the first pseudo signal from a second signal to supply a first differential signal as output; a second adaptive filter that takes the first signal as input to generate a second pseudo signal; a second subtractor that subtracts the second pseudo signal from the second signal to supply a second differential signal as output; a first step size control circuit that generates a first step size used in updating the first adaptive filter in accordance with the relation between the second pseudo signal and the second differential signal; and a second step size control circuit that generates a second step size used in updating the second adaptive filter in accordance with the relation between the first signal and the second signal.

Claims

1. A signal processing method for receiving a first signal and a second signal as input, said signal processing method comprising the steps of:

generating a first pseudo signal by means of a first adaptive filter that takes a first intermediate signal as input, generating a first differential signal by subtracting said first pseudo signal from said second signal, and using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes a second intermediate signal as input, generating a second differential signal by subtracting said second pseudo signal from said second signal, and using said second differential signal to update a coefficient of said second adaptive filter;

generating a third pseudo signal by means of a third adaptive filter that takes said first differential signal as input, generating a third differential signal by subtracting said third pseudo signal from said first signal, applying said third differential signal to said first adaptive filter as said first intermediate signal, and using said third differential signal to update a coefficient of said third adaptive filter;

generating a fourth pseudo signal by means of a fourth adaptive filter that takes said second differential signal as input, generating a fourth differential signal by subtracting said fourth pseudo signal from said first signal, applying said fourth differential signal to said second adaptive filter as said second intermediate signal, and using said fourth differential signal to update a coefficient of said fourth adaptive filter;

based on relation between signals, using a first step size to control updating of the coefficient of said first adaptive filter, using a second step size to control updating of the coefficient of said second adaptive filter, using a third step size to control updating of the coefficient of said third adaptive filter, and using a fourth step size to control updating of the coefficient of said fourth adaptive filter; and

supplying said first differential signal as output.

5. A signal processing method according to claim 1 or 2, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said first signal and said second signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said first signal and said second signal.

6. A signal processing method according to claim 1 or 2, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said first signal and said second signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal.

7. A signal processing method according to claim 1 or 2, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said first signal and said second signal.

8. A signal processing method according to any one of claims 1 to 4, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal.

9. A signal processing method according to claim 1 or 2, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with either one of the relation between said first signal and said second signal and the relation between said second pseudo signal and said second differential signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with either one of the relation between said first signal and said second signal and the relation between said fourth pseudo signal and said fourth differential signal.

10. A signal processing method according to claim 1 or 2, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said first signal and said second signal, said third step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, and said fourth step size is controlled in accordance with the relation between said first signal and said second signal.

11. A signal processing method according to claim 1 or 2, wherein said first step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, said second step size is controlled in accordance with the relation between said first signal and said second signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said first signal and said second signal.

12. A signal processing method according to claim 1 or 2, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said first signal and said second signal, said third step size is controlled in accordance with a value that is obtained by correcting the relation between said second pseudo signal and said second differential signal, and said fourth step size is controlled in accordance with the relation between said first signal and said second signal.

13. A signal processing method according to claim 1 or 2, wherein said first step size is controlled in accordance with a value that is obtained by correcting the relation between said fourth pseudo signal and said fourth differential signal, said second step size is controlled in accordance with the relation between said first signal and said second signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said first signal and said second signal.

14. A signal processing method according to claim 1 or 2, said signal processing method further comprising the steps of:

generating a delayed relation signal by delaying the relation between said first signal and said second signal; and

generating an average signal by taking average of the relation between said first signal and said second signal;

wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal;

said second step size is controlled in accordance with said average signal and a larger one of the relation between said first signal and said second signal and said first delayed signal;

said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal; and

said fourth step size is controlled in accordance with said average signal and a smaller one of the relation between said first signal and said second signal and said delayed relation signal.

21. A signal processing method according to claim 1 or 2, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal, said third step size is controlled in accordance with a value obtained by correcting the relation between said second pseudo signal and said second differential signal, and said fourth step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal.

2. A signal processing method for receiving a first signal and a second signal as input, said signal processing method comprising the steps of:

generating a first delayed signal by delaying said first signal and generating a second delayed signal by delaying said second signal;

generating a first pseudo signal by means of a first adaptive filter that takes a first intermediate signal as input, generating a first differential signal by subtracting said first pseudo signal from said second delayed signal, and using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes a second intermediate signal as input, generating a second differential signal by subtracting said second pseudo signal from said second signal, and using said second differential signal to update a coefficient of said second adaptive filter;

generating a third pseudo signal by means of a third adaptive filter that takes said first differential signal as input, generating a third differential signal by subtracting said third pseudo signal from said first delayed signal, applying said third differential signal to said first adaptive filter as said first intermediate signal, and using said third differential signal to update a coefficient of said third adaptive filter;

generating a fourth pseudo signal by means of a fourth adaptive filter that takes said second differential signal as input, generating a fourth differential signal by subtracting said fourth pseudo signal from said first signal, applying said fourth differential signal to said second adaptive filter as said second intermediate signal, and using said fourth differential signal to update a coefficient of said fourth adaptive filter;

based on relation between signals, using a first step size to control updating the coefficient of said first adaptive filter, using a second step size to control updating of the coefficient of said second adaptive filter, using a third step size to control updating of the coefficient of said third adaptive filter, and using a fourth step size to control updating of the coefficient of said fourth adaptive filter; and

supplying said first differential signal as output.

3. A signal processing method for receiving a first signal and a second signal as input, said signal processing method comprising steps of:

generating a first thinned signal by thinning out said first signal, and generating a second thinned signal by thinning out said second signal;

generating a first pseudo signal by means of a first adaptive filter that takes a first intermediate signal as input, generating a first differential signal by subtracting said first pseudo signal from said second signal, and using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes a second intermediate signal as input, generating a second differential signal by subtracting said second pseudo signal from said second thinned signal, and using said second differential signal to update a coefficient of said second adaptive filter;

generating a third pseudo signal by means of a third adaptive filter that takes said first differential signal as input, generating a third differential signal by subtracting said third pseudo signal from said first signal, applying said third differential signal to said first adaptive filter as said first intermediate signal, and using said third differential signal to update a coefficient of said third adaptive filter;

generating a fourth pseudo signal by means of a fourth adaptive filter that takes said second differential signal as input, generating a fourth differential signal by subtracting said fourth pseudo signal from said first thinned signal, applying said fourth differential signal to said second adaptive filter as said second intermediate signal; and

using said fourth differential signal to update a coefficient of said fourth adaptive filter;

based on relation between signals, using a first step size to control updating of the coefficient of said first adaptive filter, using a second step size to control updating of the coefficient of said second adaptive filter, using a third step size to control updating of the coefficient of said third adaptive filter, and using a fourth step size to control updating of the coefficient of said fourth adaptive filter; and

supplying said first differential signal as output.

15. A signal processing method according to claim 3 or 4, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal.

16. A signal processing method according to claim 3 or 4, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal.

17. A signal processing method according to claim 3 or 4, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal.

18. A signal processing method according to claim 3 or 4, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with either one of the relation between said first thinned signal and said second thinned signal and the relation between said second pseudo signal and said second differential signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with either one of the relation between said first thinned signal and said second thinned signal and the relation between said fourth pseudo signal and said fourth differential signal.

19. A signal processing method according to claim 3 or 4, wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, said second step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal, said third step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal, and said fourth step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal.

20. A signal processing method according to claim 3 or 4, wherein said first step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, said second step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal.

22. A signal processing method according to claim 3 or 4, wherein said first step size is controlled in accordance with a value that is obtained by correcting the relation between said fourth pseudo signal and said fourth differential signal, said second step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal, said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal, and said fourth step size is controlled in accordance with the relation between said first thinned signal and said second thinned signal.

23. A signal processing method according to claim 3 or 4, further comprising the steps of:

generating a delayed relation signal by delaying the relation between said first signal and said second signal; and

generating an average signal by averaging the relation between said first thinned signal and said second thinned signal;

wherein said first step size is controlled in accordance with the relation between said second pseudo signal and said second differential signal;

said second step size is controlled in accordance with said average signal and a larger one of said first delayed signal and the relation between said first thinned signal and said second thinned signal;

said third step size is controlled in accordance with the relation between said fourth pseudo signal and said fourth differential signal; and

said fourth step size is controlled in accordance with said average signal and a smaller one of the relation between said first thinned signal and said second thinned signal and said delayed relation signal.

4. A signal processing method for receiving a first signal and a second signal as input, said signal processing method comprising steps of:

generating a first delayed signal by delaying said first signal and generating a second delayed signal by delaying said second signal;

generating a first thinned signal by thinning out said first signal, and generating a second thinned out signal by thinning said second signal;

generating a first pseudo signal by means of a first adaptive filter that takes a first intermediate signal as input, generating a first differential signal by subtracting said first pseudo signal from said second delayed signal, and using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes a second intermediate signal as input, generating a second differential signal by subtracting said second pseudo signal from said second thinned signal, and using said second differential signal to update a coefficient of said second adaptive filter;

generating a third pseudo signal by means of a third adaptive filter that takes said first differential signal as input, generating a third differential signal by subtracting said third pseudo signal from said first delayed signal, applying said third differential signal to said first adaptive filter as said first intermediate signal, and using said third differential signal to update a coefficient of said third adaptive filter;

generating a fourth pseudo signal by means of a fourth adaptive filter that takes said second differential signal as input;

generating a fourth differential signal by subtracting said fourth pseudo signal from said first thinned signal, applying said fourth differential signal as said second intermediate signal to said second adaptive filter, and using said fourth differential signal to update a coefficient of said fourth adaptive filter;

based on relation between signals, using a first step size to control updating of the coefficient of said first adaptive filter, using a second step size to control updating of the coefficient of said second adaptive filter, using a third step size to control updating of the coefficient of said third adaptive filter, and using a fourth step size to control updating of the coefficient of said fourth adaptive filter; and

supplying said first differential signal as output.

24. A signal processing method comprising steps of:

using a first signal and a second signal that contains a desired signal to calculate a first index indicating relation between said first signal and said second signal;

using said first signal, said second signal, and said first index to calculate a second index indicating relation between said desired signal and signals other than said desired signal; and

using said first signal, said second signal, and said second index to extract said desired signal.

25. A signal processing method for using a first signal and a second signal containing a desired signal to extract the desired signal;

said signal processing method comprising the steps of;

using relation between said first signal and said second signal to control a first signal process that operates by taking said first signal and said second signal as input;

using the result of said first signal process to control a second signal process that operates by taking said first signal and said second signal as input.

26. A signal processing method, comprising the steps of:

generating a first pseudo signal by means of a first adaptive filter that takes a first signal as input;

generating a first differential signal by subtracting said first pseudo signal from a second signal;

using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes said first signal as input;

generating a second differential signal by subtracting said second pseudo signal from said second signal;

using said second differential signal to update a coefficient of said second adaptive filter;

using a first step size that is controlled in accordance with relation between said second pseudo signal and said second differential signal to control updating of the coefficient of said first adaptive filter;

using a second step size that is controlled in accordance with relation between said first signal and said second signal to control updating of the coefficient of said second adaptive filter; and

supplying said first differential signal as output.

27. A signal processing method, comprising the steps of generating a first delayed signal by delaying a first signal and generating a second-delayed signal by delaying a second signal;

generating a first pseudo signal by means of a first adaptive filter that takes said first delayed signal as input;

generating a first differential signal by subtracting said first pseudo signal from said second delayed signal;

using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes said first signal as input;

generating a second differential signal by subtracting said second pseudo signal from said second signal;

using said second differential signal to update a coefficient of said second adaptive filter;

using a first step size that is controlled in accordance with relation between said second pseudo signal and said second differential signal to control updating of the coefficient of said first adaptive filter;

using a second step size that is controlled in accordance with relation between said first signal and said second signal to control updating of the coefficient of said second adaptive filter; and

supplying said first differential signal as output.

28. A signal processing method, comprising the steps of:

generating a first pseudo signal by means of a first adaptive filter that takes a first signal as input;

generating a first differential signal by subtracting said first pseudo signal from a second signal;

generating a first thinned signal by thinning out said first signal;

generating a second thinned signal by thinning out said second signal;

using said first differential signal to update a coefficient of said first adaptive filter, generating a second pseudo signal by means of a second adaptive filter that takes said first thinned signal as input;

generating a second differential signal by subtracting said second pseudo signal from said second thinned signal;

using said second differential signal to update a coefficient of said second adaptive filter;

using a first step size that is controlled in accordance with relation between said second pseudo signal and said second differential signal to control updating of the coefficient of said first adaptive filter;

using a second step size that is controlled in accordance with relation between said first thinned signal and said second thinned signal to control updating of the coefficient of said second adaptive filter; and

supplying said first differential signal as output.

29. A signal processing method, comprising steps of:

generating a first delayed signal by delaying a first signal and generating a second delayed signal by delaying a second signal;

generating a first pseudo signal by means of a first adaptive filter that takes said first delayed signal as input;

generating a first differential signal by subtracting said first pseudo signal from said second delayed signal;

generating a first thinned signal by thinning out said first signal;

generating a second thinned signal by thinning out said second signal;

using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes said first thinned signal as input;

generating a second differential signal subtracting said second pseudo signal from said second thinned signal;

using said second differential signal to update a coefficient of said second adaptive filter;

using a first step size that is controlled in accordance with relation between said second pseudo signal and said second differential signal to control updating of the coefficient of said first adaptive filter;

using a second step size that is controlled in accordance with relation between said first thinned signal and said second thinned signal to control updating of the coefficient of said second adaptive filter; and

supplying said first differential signal as output.

30. A signal processor comprising:

a first calculation circuit for receiving, as input, a first signal and a second signal that contains a desired signal and calculating a first index that indicates relation between said first signal and said second signal;

a second calculation circuit for receiving said first signal, said second signal, and said first index as input and calculating a second index that indicates relation between said desired signal and signals other than the desired signal; and

a signal processing circuit for receiving said first signal, said second signal, and said second index as input for extracting said desired signal.

31. A signal processor for receiving, as input, a first signal and a second signal that contains a desired signal and extracting the desired signal;

said signal processor comprising;

a calculation circuit for calculating relation between said first signal and said second signal;

a first signal processing means for receiving said first signal and said second signal as input; and

a second signal processing means for receiving said first signal and said second signal;

wherein an output of said calculation circuit is used to control operation of said first signal processing means, and an output of said first signal processing means is used to control operation of said second signal processing means.

32. A signal processor comprising:

a first adaptive filter for taking a first signal as input and generating a first pseudo signal;

a first subtractor for generating a first differential signal by subtracting said first pseudo signal from a second signal;

a second adaptive filter for taking said first signal as input and generating a second pseudo signal;

a second subtractor for generating a second differential signal by subtracting said second pseudo signal from said second signal;

a first step size control means for generating a first step size in accordance with relation between said second pseudo signal and said second differential signal; and

a second step size control means for generating a second step size in accordance with relation between said first signal and said second signal;

wherein said first differential signal and said first step size are used to update a coefficient of said first adaptive filter;

said second differential signal and said second step size are used to update a coefficient of said second adaptive filter; and

said first differential signal is supplied as output.

34. A signal processor according to claim 32 or 33, further comprising:

first delay means for conferring a delay to said second signal that is applied as input to said first adaptive filter; and

a second delay means for conferring a delay to said second signal that is applied as input to said first subtractor.

50. A signal processor according to any one of claims 32 to 34 for canceling noise, wherein:

said first signal is a first received sound signal received as input from a speech input terminal;

said second signal is a second received sound signal received as input from a reference input terminal;

said first step size control means supplies a large step size to said first adaptive filter to speed convergence when it is determined based on signal-to-noise relation in said first received sound signal that a noise signal is greater than a speech signal in said first received sound signal, and supplies a small step size to said first adaptive filter when it is determined that a noise signal is smaller than a speech signal in said first received sound signal; and

said second step size control means supplies a large step size to said second adaptive filter to speed convergence when it is determined based on signal-to-noise relation in said second received sound signal that a speech signal is greater than a noise signal in said second received sound signal, and supplies a small step size to said second adaptive filter when it is determined that a speech signal is smaller than a noise signal.

52. A signal processor according to any one of claims 32 to 49, wherein:

said first signal is an echo signal received as input from a first input terminal;

said second signal is a reference signal received as input from a second input terminal; and

a signal is supplied as output from which the echo has been cancelled.

61. A speech recognition device, comprising:

the signal processor according to any one of claims 32 to 49; and

a speech recognition means for implementing speech recognition of signals that are supplied from said signal processor and supplying the results of speech recognition.

62. A robot, said robot comprising:

a drive means for driving the operation of prescribed parts of the robot;

operation control means for controlling said drive means; and

a speech recognition device according to claim 61;

wherein said operation control means takes the results of speech recognition that are supplied as output from said speech recognition device, and controls said drive means based on said results of speech recognition.

33. A signal processor comprising:

a first adaptive filter for taking a first signal as input and generating a first pseudo signal;

a first subtractor for generating a first differential signal by subtracting said first pseudo signal from a second signal;

a first thinning means for generating a first thinned signal by thinning out said first signal;

a second thinning means for generating a second thinned signal by thinning out said second signal;

a second adaptive filter for taking said first thinned signal as input and generating a second pseudo signal;

a second subtractor for generating a second differential signal by subtracting said second pseudo signal from said second thinned signal;

a first step size control means for generating a first step size in accordance with relation between said second pseudo signal and said second differential signal; and

a second step size control means for generating a second step size in accordance with relation between said first thinned signal and said second thinned signal;

wherein said first differential signal and said first step size are used to update a coefficient of said first adaptive filter;

said second differential signal and said second step size are used to update a coefficient of said second adaptive filter; and

said first differential signal is supplied as output.

35. A signal processor for receiving a first signal and a second signal as input, said signal processor comprising:

a first adaptive filter for taking a first intermediate signal as input and generating a first pseudo signal;

a first subtractor for generating a first differential signal by subtracting said first pseudo signal from said second signal;

a second adaptive filter for taking a second intermediate signal as input and generating a second pseudo signal;

a second subtractor for generating a second differential signal by subtracting said second pseudo signal from said second signal;

a third adaptive filter for taking said first differential signal as input and generating a third pseudo signal;

a third subtractor for generating a third differential signal by subtracting said third pseudo signal from said first signal and supplying said third differential signal to said first adaptive filter as said first intermediate signal;

a fourth adaptive filter for taking said second differential signal as input and generating a fourth pseudo signal;

a fourth subtractor for generating a fourth differential signal by subtracting said fourth pseudo signal from said first signal and supplying said fourth differential signal to said second adaptive filter as said second intermediate signal; and

a step size control means for, based on relation between signals, generating a first step size, a second step size, a third step size, and a fourth step size;

wherein said first differential signal and said first step size are used to update a coefficient of said first adaptive filter;

said second differential signal and said second step size are used to update a coefficient of said second adaptive filter;

said third differential signal and said third step size are used to update a coefficient of said third adaptive filter;

said fourth differential signal and said fourth step size are used to update a coefficient of said fourth adaptive filter; and

said first differential signal is supplied as output.

36. A signal processor according to claim 35, further comprising:

a first delay circuit for conferring a delay to said first signal that is applied as input to said third subtractor; and

a second delay circuit for conferring a delay to said second signal that is applied as input to said first subtractor.

37. A signal processor according to claim 35 or 36, wherein said step size control means comprises:

a first step size control circuit for generating said first step size in accordance with the relation between said second pseudo signal and said second differential signal;

a second step size control circuit for generating said second step size in accordance with the relation between said first signal and said second signal;

a third step size control circuit for generating said third step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal; and

a fourth step size control circuit for generating said fourth step size in accordance with the relation between said first signal and said second signal.

38. A signal processor according to claim 35 or 36, wherein said step size control means comprises:

a first step size control circuit for generating said first step size in accordance with the relation between said second pseudo signal and said second differential signal;

a second step size control circuit for generating said second step size in accordance with the relation between said first signal and said second signal;

a third step size control circuit for generating said third step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal; and

a fourth step size control circuit for generating said fourth step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal.

39. A signal processor according to claim 35 or 36, wherein said step size control means comprises:

a first step size control circuit for generating said first step size in accordance with the relation between said second pseudo signal and said second differential signal;

a second step size control circuit for generating said second step size in accordance with the relation between said second pseudo signal and said second differential signal;

a third step size control circuit for generating said third step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal; and

a fourth step size control circuit for generating said fourth step size in accordance with the relation between said first signal and said second signal.

40. A signal processor according to claim 35 or 36, wherein said step size control means comprises:

a first step size control circuit for generating said first step size in accordance with the relation between said second pseudo signal and said second differential signal;

a second step size control circuit for generating said second step size in accordance with the relation between said second pseudo signal and said second differential signal;

a third step size control circuit for generating said third step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal; and

a fourth step size control circuit for generating said fourth step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal.

41. A signal processor according to claim 35 or 36, wherein said step size control means comprises:

a first step size control circuit for generating said first step size in accordance with the relation said second pseudo signal and said second differential signal;

a second step size control circuit for generating said second step size in accordance with either one of the relation between said first signal and said second signal or the relation between said second pseudo signal and said second differential signal;

a third step size control circuit for generating said third step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal; and

a fourth step size control circuit for generating said fourth step size in accordance with either one of the relation between said first signal and said second signal or the relation between said fourth pseudo signal and said fourth differential signal.

42. A signal processor according to claim 35 or 36, wherein said step size control means comprises:

a first step size control circuit for generating said first step size in accordance with the relation between said second pseudo signal and said second differential signal;

a second step size control circuit for generating said second step size in accordance with the relation between said first signal and said second signal;

a third step size control circuit for generating said third step size in accordance with the relation between said second pseudo signal and said second differential signal; and

a fourth step size control circuit for generating said fourth step size in accordance with the relation between said first signal and said second signal.

43. A signal processor according to claim 35 or 36, wherein said step size control means comprises:

a first step size control circuit for generating said first step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal;

a second step size control circuit for generating said second step size in accordance with the relation between said first signal and said second signal;

a third step size control circuit for generating said third step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal; and

a fourth step size control circuit for generating said fourth step size in accordance with the relation between said first signal and said second signal.

44. A signal processor according to claim 35 or 36, wherein said step size control means comprises:

a first step size control circuit for generating said first step size in accordance with the relation between said second pseudo signal and said second differential signal;

a second step size control circuit for generating said second step size in accordance with the relation between said first signal and said second signal;

a third step size control circuit for generating said third step size in accordance with a value obtained by correcting the relation between said second pseudo signal and said second differential signal; and

a fourth step size control circuit for generating said fourth step size in accordance with the relation between said first signal and said second signal.

45. A signal processor according to claim 35 or 36, wherein said step size control means comprises:

a first step size control circuit for generating said first step size in accordance with a value obtained by correcting the relation between said fourth pseudo signal and said fourth differential signal;

a second step size control circuit for generating said second step size in accordance with the relation between said first signal and said second signal;

a third step size control circuit for generating said third step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal; and

a fourth step size control circuit for generating said fourth step size in accordance with the relation between said first signal and said second signal.

46. A signal processor according to claim 35 or 36, further comprising:

delay means for generating a delayed signal by delaying the relation between said first signal and said second signal; and

averaging means for generating an average signal by averaging the relation between said first signal and said second signal;

wherein said step size control means includes;

a first step size control circuit for generating said first step size in accordance with the relation between said second pseudo signal and said second differential signal;

a second step size control circuit for generating said second step size in accordance with said average signal and a larger one of said delayed signal and the relation between said first signal and said second signal;

a third step size control circuit for generating said third step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal; and

a fourth step size control circuit for generating said fourth step size in accordance with said average signal and a smaller one of said delayed signal and the relation between said first signal and said second signal.

47. A signal processor according to claim 35 or 36, further comprising:

a first delay means for generating a delayed signal by delaying the relation between said first signal and said second signal;

an averaging means for generating an average signal by averaging the relation between said first signal and said second signal;

wherein said step size control means includes;

a first step size control circuit for generating said first step size in accordance with the relation between said second pseudo signal and said second differential signal;

a second step size control circuit for generating said second step size in accordance with said average signal and a larger one of said delayed signal and the relation between said first signal and said second signal, and for generating a fourth step size in accordance with said average signal and a smaller one of said delayed signal and the relation between said first signal and said second signal; and

a third step size control circuit for generating said third step size in accordance with the relation between said fourth pseudo signal and said fourth differential signal.

48. A signal processor according to any one of claims 35, 36, and 40, further comprising:

a first thinning means for thinning out said first signal that is applied as input to said fourth subtractor; and

a second thinning means for thinning out said second signal that is applied as input to said second subtractor.

49. A signal processor according to any one of claims 37, 38, 39, 41, 42, 43, 44, 45, 46, and 47, further comprising:

first thinning means for thinning out said first signal that is applied as input to said fourth subtractor; and

second thinning means for thinning out said second signal that is applied as input to said second subtractor;

wherein the relation between said first signal following thinning and said second signal following thinning is used as said relation between said first signal and said second signal.

51. A signal processor according to any one of claims 35 to 49 for canceling noise, wherein:

said first signal is a first received sound signal received as input from a speech input terminal;

said second signal is a second received sound signal received as input from a reference input terminal;

said first step size control circuit supplies a large step size to said first adaptive filter to speed convergence when it is determined based on signal-to-noise relation in said first received sound signal that a noise signal is greater than a speech signal in said first received sound signal, and supplies a small step size to said first adaptive filter when it is determined that a noise signal is smaller than a speech signal in said first received sound signal;

said second step size control circuit supplies a large step size to said second adaptive filter to speed convergence when it is determined based on signal-to-noise relation in said second received sound signal that a speech signal is greater than a noise signal in said second received sound signal; and

supplies a small step size to said second adaptive filter when it is determined that a speech signal is smaller than a noise signal;

said third step size control circuit supplies a large step size to said third adaptive filter to speed convergence when it is determined based on the signal-to-noise relation in said first received sound signal that a noise signal is greater than a speech signal in said first received sound signal, and supplies a small step size to said third adaptive filter when it is determined that a noise signal is smaller than a speech signal in said first received sound signal; and

said fourth step size control circuit supplies a large step size to said fourth adaptive filter to speed convergence when it is determined based on the signal-to-noise relation in said second received sound signal that a speech signal is greater than a noise signal in said second received sound signal, and supplies a small step size to said fourth adaptive filter when it is determined that a speech signal is smaller than a noise signal.

53. A program for causing a computer that constitutes a signal processor to execute the processes of:

using a first signal and a second signal that contains a desired signal to calculate a first index indicating the relation between said first signal and said second signal;

using said first signal, said second signal, and said first index to calculate a second index indicating the relation between said desired signal and signals other than the desired signal; and

using said first signal, said second signal, and said second index to extract said desired signal.

54. A program for causing a computer, which constitutes a signal processor for using a first signal and a second signal that contains a desired signal to extract the desired signal, to execute the processes of:

using the relation between said first signal and said second signal to control a first signal process that operates by taking said first signal and said second signal as input; and

using the results of said first signal process to control a second signal process that operates by taking said first signal and said second signal as input.

55. A program for causing a computer that constitutes a signal processor to execute the processes of:

generating a first pseudo signal by means of a first adaptive filter that takes a first signal as input, generating a first differential signal by subtracting said first pseudo signal from a second signal, and using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes said first signal as input, generating a second differential signal by subtracting said second pseudo signal from said second signal; and

using said second differential signal to update a coefficient of said second adaptive filter;

using a first step size that is controlled in accordance with the relation between said second pseudo signal and said second differential signal to control updating of the coefficient of said first adaptive filter;

using a second step size that is controlled in accordance with the relation between said first signal and said second signal to control updating of a coefficient of said second adaptive filter; and

supplying said first differential signal as output.

56. A program for causing a computer that constitutes a signal processor to execute the processes of:

generating a first pseudo signal by means of a first adaptive filter that takes a first signal as input, generating a first differential signal by subtracting said first pseudo signal from a second signal, and using said first differential signal to update a coefficient of said first adaptive filter;

generating a first thinned signal by thinning out said first signal;

generating a second thinned signal by thinning out said second signal;

generating a second pseudo signal by means of a second adaptive filter that takes said first thinned signal as input generating a second differential signal by subtracting said second pseudo signal from said second thinned signal, and using said second differential signal to update a coefficient of said second adaptive filter;

using a first step size that is controlled in accordance with the relation between said second pseudo signal and said second differential signal to control updating of the coefficient of said first adaptive filter;

using a second step size that is controlled in accordance with the relation between said first thinned signal and said second thinned signal to control updating of the coefficient of said second adaptive filter; and

supplying said first differential signal as output.

57. A program for causing a computer that constitutes a signal processor that takes a first signal and a second signal as input to execute the processes of:

generating a first pseudo signal by means of a first adaptive filter that takes a first intermediate signal as input, generating a first differential signal by subtracting said first pseudo signal from said second signal, and using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes a second intermediate signal as input, generating a second differential signal by subtracting said second pseudo signal from said second signal, and using said second differential signal to update a coefficient of said second adaptive filter;

generating a third pseudo signal by means of a third adaptive filter that takes said first differential signal as input, generating a third differential signal by subtracting said third pseudo signal from said first signal, applying said third differential signal as said first intermediate signal to said first adaptive filter, and using said third differential signal to update a coefficient of said third adaptive filter;

generating a fourth pseudo signal by means of a fourth adaptive filter that takes said second differential signal as input, generating a fourth differential signal by subtracting said fourth pseudo signal from said first signal, applying said fourth differential signal as said second intermediate signal to said second adaptive filter, and using said fourth differential signal to update a coefficient of said fourth adaptive filter;

based on the relations between signals, using a first step size to control the updating of the coefficient of said first adaptive filter, using a second step size to control updating of the coefficient of said second adaptive filter;

using a third step size to control updating of the coefficient of said third adaptive filter, and using a fourth step size to control updating of the coefficient of said fourth adaptive filter; and

supplying said first differential signal as output.

58. A program for causing a computer that constitutes a signal processor that takes a first signal and a second signal as input to execute the processes of:

generating a first delayed signal by delaying said first signal and generating a second delayed signal by delaying said second signal;

generating a first pseudo signal by means of a first adaptive filter that takes a first intermediate signal as input, generating a first differential signal by subtracting said first pseudo signal from said second delayed signal, and using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes a second intermediate signal as input, generating a second differential signal by subtracting said second pseudo signal from said second signal, and using said second differential signal to update a coefficient of said second adaptive filter;

generating a third pseudo signal by means of a third adaptive filter that takes said first differential signal as input, generating a third differential signal by subtracting said third pseudo signal from said first delayed signal, applying said third differential signal as said first intermediate signal to said first adaptive filter, and using said third differential signal to update a coefficient of said third adaptive filter;

generating a fourth pseudo signal by means of a fourth adaptive filter that takes said second differential signal as input, generating a fourth differential signal by subtracting said fourth pseudo signal from said first signal, applying said fourth differential signal as said second intermediate signal to said second adaptive filter, and using said fourth differential signal to update a coefficient of said fourth adaptive filter;

based on the relations between signals, using a first step size to control updating of the coefficient of said first adaptive filter, using a second step size to control updating of the coefficient of said second adaptive filter, using a third step size to control updating of the coefficient of said third adaptive filter, and using a fourth step size to control updating of the coefficient of said fourth adaptive filter; and

supplying said first differential signal as output.

59. A program for causing a computer that constitutes a signal processor that takes a first signal and a second signal as input to execute the processes of:

generating a first thinned signal by thinning out said first signal, and generating a second thinned signal by thinning out said second signal;

generating a first pseudo signal by means of a first adaptive filter that takes a first intermediate signal as input, generating a first differential signal by subtracting said first pseudo signal from said second signal, and using said first differential signal to update the coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes a second intermediate signal as input, generating a second differential signal by subtracting said second pseudo signal from said second thinned signal, and using said second differential signal to update a coefficient of said second adaptive filter;

generating a third pseudo signal by means of a third adaptive filter that takes said first differential signal as input, generating a third differential signal by subtracting said third pseudo signal from said first signal, applying said third differential signal as said first intermediate signal to said first adaptive filter, and using said third differential signal to update a coefficient of said third adaptive filter;

generating a fourth pseudo signal by means of a fourth adaptive filter that takes a second differential signal as input, generating a fourth differential signal by subtracting said fourth pseudo signal from said first thinned signal, applying said fourth differential signal as said second intermediate signal to said second adaptive filter, using said fourth differential signal to update a coefficient of said fourth adaptive filter;

based on relations between signals, using a first step size to control updating of the coefficient of said first adaptive filter, using a second step size to control updating of the coefficient of said second adaptive filter, using a third step size to control updating of the coefficient of said third adaptive filter, and using a fourth step size to control updating of the coefficient of said fourth adaptive filter; and

supplying said first differential signal as output.

60. A program for causing a computer that constitutes a signal processor that takes a first signal and a second signal as input to execute the processes of:

generating a first delayed signal by delaying said first signal and generating a second delayed signal by delaying said second signal;

generating a first thinned signal by thinning out said first signal, and generating a second thinned signal by thinning out said second signal;

generating a first pseudo signal by means of a first adaptive filter that takes a first intermediate signal as input, generating a first differential signal by subtracting said first pseudo signal from said second delayed signal, and using said first differential signal to update a coefficient of said first adaptive filter;

generating a second pseudo signal by means of a second adaptive filter that takes a second intermediate signal as input, generating a second differential signal by subtracting said second pseudo signal from said second thinned signal, and using said second differential signal to update a coefficient of said second adaptive filter;

generating a third pseudo signal by means of a third adaptive filter that takes said first differential signal as input, generating a third differential signal by subtracting said third pseudo signal from said first delayed signal, applying said third differential signal as said first intermediate signal to said first adaptive filter, and using said third differential signal to update a coefficient of said third adaptive filter;

generating a fourth pseudo signal by means of a fourth adaptive filter that takes said second differential signal as input, generating a fourth differential signal by subtracting said fourth pseudo signal from said first thinned signal, applying said fourth differential signal as said second intermediate signal to said second adaptive filter, and using said fourth differential signal to update a coefficient of said fourth adaptive filter;

based on the relations between signals, using a first step size to control updating of the coefficient of said first adaptive filter, using a second step size to control updating of the coefficient of said second adaptive filter, using a third step size to control updating of the coefficient of said third adaptive filter, and using a fourth step size to control updating of the coefficient of said fourth adaptive filter;

supplying said first differential signal as output.