Methods and systems for considering information about an expected response when performing speech recognition

• US 20060178886A1
• Filed: 01/13/2006
• Published: 08/10/2006
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Vocollect, Inc. (Honeywell International Inc.)
• Original Assignee: Vocollect, Inc. (Honeywell International Inc.)
• Inventors: Braho, Keith, El-Jaroudi, Amro
• Granted Patent: US 8,200,495 B2
• Time in Patent Office: Days
• US Class Current: 704/246
• CPC Class Codes: G10L 15/065 Adaptation
• CPC Class Codes: G10L 15/22 Procedures used during a speech recognition process, e.g. man-machine dialogue
• CPC Class Codes: G10L 2015/228 of application context

Abstract

A speech recognition system receives and analyzes speech input from a user in order to recognize and accept a response from the user. Under certain conditions, information about the response expected from the user may be available. In these situations, the available information about the expected response is used to modify the behavior of the speech recognition system by taking this information into account. The modified behavior of the speech recognition system according to the invention has several embodiments including: comparing the observed speech features to the models of the expected response separately from the usual hypothesis search in order to speed up the recognition system; modifying the usual hypothesis search to emphasize the expected response; updating and adapting the models when the recognized speech matches the expected response to improve the accuracy of the recognition system.

Claims

1. A method for recognizing speech comprising the steps of:

generating features of input speech;

comparing the input speech features to features of an expected response to generate an associated confidence factor;

comparing the confidence factor to an acceptance threshold for accepting the expected response as the result of the speech recognition.

2. The method of claim 1 wherein the comparison of the input speech features includes using models of speech in a match/search algorithm.

3. The method of claim 2 wherein the comparison of the input speech features includes using only a model or models associated with the expected response.

4. The method of claim 1 further comprising adjusting the acceptance threshold based on the comparison of the input speech features to features of an expected response in order to affect the acceptance of the expected response.

5. The method of claim 4 further comprising adjusting the acceptance threshold at least one of upwardly or downwardly.

6. The method of claim 1 further comprising, if the comparison to the expected response does not yield a confidence factor exceeding the acceptance threshold, comparing the input speech features to features of additional responses.

7. A method for recognizing speech comprising the steps of:

analyzing a speech input to generate features of the input speech;

maintaining a set of responses which the input speech may match;

comparing the input speech features to a smaller subset of the set of responses to generate a hypothesis and associated confidence factor;

comparing the confidence factor to an acceptance threshold for accepting the hypothesis based on the comparison.

8. The method of claim 7 wherein the smaller subset includes only a single expected response.

9. A method for recognizing speech comprising the steps of:

in a speech dialog, determining an expected response to be received as input speech from a user;

based upon the expected response, modifying a speech recognition match/search algorithm to tailor it to the expected response;

processing input speech from a user with the modified match/search algorithm to generate a hypothesis and confidence factor for the input speech.

10. The method of claim 9 further comprising comparing the hypothesis confidence factor to an acceptance threshold for accepting the hypothesis.

11. The method of claim 9 wherein the match/search algorithm processes the input speech through a plurality of states and the method further comprises modifying transition probabilities associated with transitions between multiple states in the match/search algorithm.

12. The method of claim 9 wherein the match/search algorithm processes the input speech through a plurality of states and the method further comprises modifying initial state probabilities associated with a path through multiple states in the match/search algorithm.

13. The method of claim 9 wherein the match/search algorithm utilizes multiple paths through acoustic models for the input speech and the method further comprises modifying the acoustic models based on the expected response.

14. The method of claim 9 wherein the match/search algorithm utilizes multiple paths through acoustic models for the input speech and the method further comprises modifying the insertion penalty associated with a given acoustic model.

15. The method of claim 9 wherein processing of the input speech results in frames of the features of the input speech and the method further comprises utilizing multiple paths through acoustic models for the input speech feature frames to generate scores , and applying at least one of a bias or penalty per frame to the input speech to affect the scores of paths through the models.

16. A method for improving speech recognition comprising the steps of:

receiving input speech from a user and generating features of the input speech;

comparing the input speech features to features of an expected response;

to determine if the input speech matches the expected response;

based upon the comparison, adapting acoustic models using the features of the input speech.

17. The method of claim 16 wherein the comparison includes generating a confidence factor associated with the expected response.

18. The method of claim 16 wherein the match/search algorithm processes the input speech through a plurality of models with states, and the method further comprises modifying statistics associated with the model states.

19. The method of claim 17 wherein the state statistics are modified by combining original statistics with new statistics associated with the input speech.

20. The method of claim 16 wherein the expected response is a single response.

21. The method of claim 16 wherein the expected response is a one of a set of multiple responses.

22. The method of claim 16 wherein the expected response is obtained by at least one of evaluating an expression or retrieving the expected response from a table or data structure prior to comparing the speech features to the expected response.

23. The method of claim 16 wherein the expected response is dynamically determined prior to comparing the speech features to the expected response.

24. The method of claim 16 wherein the match/search algorithm uses acoustic models that are adapted by creating new models based upon the input speech.

25. The method of claim 24 wherein the new models are created by adapting existing models using existing features and new features of the input speech.

26. The method of claim 24 wherein the new models are created by using only information from new features of the input speech.

27. The method of claim 16 wherein the adapting step occurs only if the comparison meets specific criteria.

28. The method of claim 27 wherein the adapting step occurs if the confidence factor of the hypothesis exceeds a minimum amount or falls in a specific range.

29. The method of claim 27 wherein the adapting step occurs if a minimum number of successful comparisons of the input speech to the expected response have occurred.

30. The method of claim 16 wherein the models are adapted for an individual user by performing adaptation using speech data only from that user.

31. An apparatus for recognizing speech comprising:

circuitry for generating features of input speech;

processing circuitry operable for comparing the input speech features to features of an expected response to generate an associated confidence factor and for comparing the confidence factor to an acceptance threshold for accepting the expected response as the recognized speech.

32. The apparatus of claim 31 wherein the comparison of the input speech features includes using models of speech in a match/search algorithm.

33. The apparatus of claim 32 wherein the comparison of the input speech features includes using only a model or models associated with the expected response.

34. The apparatus of claim 31 wherein the processing circuitry is further operable to adjust the acceptance threshold based on the comparison of the input speech features to features of an expected response in order to affect the acceptance of the expected response.

35. The apparatus of claim 34 wherein the acceptance threshold is adjusted at least one of upwardly or downwardly.

36. The apparatus of claim 31 wherein the processing circuitry compares the input speech features to features of additional responses, if the comparison to the expected response does not yield a confidence factor exceeding the acceptance threshold.

37. An apparatus for recognizing speech comprising:

circuitry for analyzing a speech input to generate features of the input speech;

a set of stored responses which the input speech may match;

processing circuitry operable for comparing the input speech features to a smaller subset of the set of responses to generate a hypothesis and associated confidence factor and for comparing the confidence factor to an acceptance threshold to accepting or deny the hypothesis based on the comparison.

38. The apparatus of claim 37 wherein the smaller subset includes only a single expected response.

39. An apparatus for recognizing speech comprising:

processing circuitry including a match/search algorithm for performing speech recognition;

the match search algorithm being dynamically modifiable based on an expected response to be received as input speech from a user and further being operable for processing input speech from a user as modified to generate a hypothesis and confidence factor for the input speech.

40. The apparatus of claim 39 wherein the processing circuitry is further operable for comparing the hypothesis confidence factor to an acceptance threshold for accepting the hypothesis.

41. The apparatus of claim 39 wherein the match/search algorithm processes the input speech through a plurality of states and is modifiable by modifying transition probabilities associated with transitions between multiple states in the match/search algorithm.

42. The apparatus of claim 39 wherein the match/search algorithm processes the input speech through a plurality of states and is modifiable by modifying initial state probabilities associated with a path through multiple states in the match/search algorithm.

43. The apparatus of claim 39 wherein the match/search algorithm utilizes multiple paths through acoustic models for the input speech and is modifiable by modifying the acoustic models based on the expected response.

44. The apparatus of claim 39 wherein the match/search algorithm utilizes multiple paths through acoustic models for the input speech and is modifiable by modifying the insertion penalty associated with a given acoustic model.

45. The apparatus of claim 39 wherein the processing circuitry creates frames of the features of the input speech and the match/search algorithm utilizes multiple paths through acoustic models for the input speech feature frames to generate scores, the algorithm applying at least one of a bias or penalty per frame to the input speech to affect the scores of paths through the models.

46. An apparatus for recognizing speech comprising:

circuitry for generating features of input speech from a user;

processing circuitry including a match/search algorithm having acoustic models;

the processing circuitry operable for comparing the input speech features to features of an expected response to determine if the input speech matches the expected response and for adapting acoustic models of the algorithm using the features of the input speech based on the comparison.

47. The apparatus of claim 46 wherein the comparison includes generating a confidence factor associated with the expected response.

48. The apparatus of claim 46 wherein the match/search algorithm processes the input speech through a plurality of models with states, and the acoustic models are adapted by modifying statistics associated with the model states.

49. The apparatus of claim 48 wherein the state statistics are modified by combining original statistics with new statistics associated with the input speech.

50. The apparatus of claim 46 wherein the expected response is a single response.

51. The apparatus of claim 46 wherein the expected response is a one of a set of multiple responses.

52. The apparatus of claim 46 wherein the expected response is obtained by at least one of evaluating an expression or retrieving the expected response from a table or data structure prior to comparing the speech features to the expected response.

53. The apparatus of claim 46 wherein the expected response is dynamically determined prior to comparing the speech features to the expected response.

54. The apparatus of claim 46 wherein the acoustic models are adapted by creating new models based upon the input speech.

55. The apparatus of claim 54 wherein the new models are created by adapting existing models using existing features and new features of the input speech.

56. The apparatus of claim 54 wherein the new models are created by using only information from new features of the input speech.

57. The apparatus of claim 46 wherein the adaptation occurs only if the comparison meets specific criteria.

58. The apparatus of claim 57 wherein the adaptation occurs if the confidence factor of the hypothesis exceeds a minimum amount or falls in a specific range.

59. The apparatus of claim 57 wherein the adapting step occurs if a minimum number of successful comparisons of the input speech to the expected response have occurred.

60. The apparatus of claim 46 wherein the models are adapted for an individual user by performing adaptation using speech data only from that user.