Method of determining uncertainty associated with acoustic distortion-based noise reduction

• US 20070106504A1
• Filed: 12/20/2006
• Published: 05/10/2007
• Est. Priority Date: 05/20/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Deng, Li, Acero, Alejandro, Droppo, James
• Granted Patent: US 7,289,955 B2
• Time in Patent Office: Days
• US Class Current: 704/226
• CPC Class Codes: G10L 15/20 Speech recognition techniques specially adapted for robustness in adverse environments, e.g. in noise, of stress induced speech G10L21/02 takes precedence
• CPC Class Codes: G10L 21/0208 Noise filtering

Abstract

A method and apparatus are provided for determining uncertainty in noise reduction based on a parametric model of speech distortion. The method is first used to reduce noise in a noisy signal. In particular, noise is reduced from a representation of a portion of a noisy signal to produce a representation of a cleaned signal by utilizing an acoustic environment model. The uncertainty associated with the noise reduction process is then computed. In one embodiment, the uncertainty of the noise reduction process is used, in conjunction with the noise-reduced signal, to decode a pattern state.

Claims

1. A method of reducing noise in a noisy signal, the method comprising:

reducing noise in a representation of a portion of the noisy signal to produce a representation of a portion of a noise-reduced signal comprising a representation of delta features of the noise-reduced signal using an acoustic-environment model; and

identifying an uncertainty associated with reducing the noise.

2. The method of claim 1 further comprising

using the uncertainty to adjust a probability distribution to form a modified probability distribution;

and

using the representation of a portion of the noise-reduced signal and the modified probability distribution to decode a pattern state.

4. The method of claim 1 wherein identifying an uncertainty comprises identifying an uncertainty associated with a delta feature of the noise-reduced signal.

5. The method of claim 1 wherein the representation of a portion of a noise-reduced signal further comprises a representation of acceleration features of the noise-reduced signal.

6. The method of claim 5 wherein identifying an uncertainty comprises identifying an uncertainty associated with an acceleration feature of the noise-reduced signal.

7. The method of claim 1 wherein reducing noise comprises using a prior model of dynamic aspects of clean signals.

3. (canceled)

8. A computer-readable medium having computer-executable instructions for performing steps comprising:

converting a frame of a noisy signal into a feature vector comprising at least two components;

reducing noise in a component of the feature vector for the noisy signal to produce a component of a feature vector for a cleaned signal by utilizing an acoustic distortion model;

determining a delta feature of the cleaned signal; and

identifying an uncertainty associated with reducing the noise from the component.

9. The computer-readable medium of claim 8 wherein the computer-executable instructions perform further steps comprising:

determining a probability component of a probability for a phonetic state based in part on the component for the cleaned signal and the uncertainty associated with reducing the noise from the component; and

using the probability component to determine the probability of the phonetic state regardless of the value of the uncertainty.

10. The computer-readable medium of claim 9 wherein determining a probability component comprises defining a probability distribution based in part on the uncertainty.

11. The computer-readable medium of claim 10 wherein defining a probability distribution comprises adding the uncertainty to a variance of a probability distribution.

13. The computer-readable medium of claim 8 wherein the computer-executable instructions perform a further step comprising determining an uncertainty of the delta feature of the cleaned signal.

14. The computer-readable medium of claim 8 wherein the computer-executable instructions perform a further step comprising determining an acceleration feature of the cleaned signal.

15. The computer-readable medium of claim 14 wherein the computer-executable instructions perform a further step comprising determining an uncertainty of the acceleration feature of the cleaned signal.

16. The computer-readable medium of claim 8 wherein reducing noise from a component further comprises utilizing a prior model of dynamic aspects of a clean signal.

12. (canceled)

17. A method of reducing noise in a noisy signal, the method comprising:

reducing noise in a representation of a portion of the noisy signal to produce a representation of a portion of a noise-reduced signal comprising a representation of acceleration features of the noise-reduced signal using an acoustic-environment model; and

identifying an uncertainty associated with reducing the noise.

18. A method of reducing noise in a noisy signal, the method comprising:

reducing noise in a representation of a portion of the noisy signal to produce a representation of a portion of a noise-reduced signal using an acoustic-environment model, reducing noise comprising using a prior model of dynamic aspects of clean signals; and

identifying an uncertainty associated with reducing the noise.

19. A computer-readable medium having computer-executable instructions for performing steps comprising:

converting a frame of a noisy signal into a feature vector comprising at least two components;

reducing noise in a component of the feature vector for the noisy signal to produce a component of a feature vector for a cleaned signal by utilizing an acoustic distortion model;

determining an acceleration feature of the cleaned signal; and

identifying an uncertainty associated with reducing the noise from the component.

20. The computer-readable medium of claim 19 wherein the computer-executable instructions perform a further step comprising determining an uncertainty of the acceleration feature of the cleaned signal.

21. A computer-readable medium having computer-executable instructions for performing steps comprising:

converting a frame of a noisy signal into a feature vector comprising at least two components;

reducing noise in a component of the feature vector for the noisy signal to produce a component of a feature vector for a cleaned signal by utilizing an acoustic distortion model and a prior model of dynamic aspects of a clean signal; and

identifying an uncertainty associated with reducing the noise from the component.