Method and device for objective speech quality assessment without reference signal

• US 20030171922A1
• Filed: 03/05/2003
• Published: 09/11/2003
• Est. Priority Date: 09/06/2000
• Status: Active Grant

• Current Assignee: Koninklijke KPN NV
• Original Assignee: Koninklijke KPN NV
• Inventors: Hekstra, Andries Pieter, Beerends, John Gerard
• Granted Patent: US 7,024,352 B2
• Time in Patent Office: Days
• US Class Current: 704/233
• CPC Class Codes: G10L 19/00 Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H
• CPC Class Codes: G10L 25/69 for evaluating synthetic or decoded voice signals

Abstract

A method of and a device for output based objective speech quality assessment, wherein a degraded output speech signal comprising a speech information portion, is compared (5) with a reference signal retrieved from the output speech signal. The reference signal is provided by perceptual approximation of the speech information portion of the output speech signal using a speech recoder (2) producing a reference speech signal of finite bitrate. In a preferred embodiment, the speech recorder (2) is a speech codec.

Claims

1. A method of output based objective speech quality assessment, wherein a degraded output speech signal comprising a speech information portion is compared with a reference signal retrieved from said output speech signal, characterized in that said reference signal is provided by perceptual approximation of said speech information portion of said output speech signal using a speech recoder producing a reference speech signal of finite bitrate.

2. A method according to claim 1, wherein said reference speech signal is provided by recoding of said output speech signal using a reference speech codec as a speech recoder.

3. A method according to claim 1 or 2, wherein said recoder is of a type that is essentially transparent for clean, undistorted speech signals and essentially non-transparent for distorted speech signals in a degree that is a measure of the distortedness of said speech signal.

4. A method according to claim 1, 2 or 3, wherein macro-properties are retrieved representative of said output speech signal, and wherein said macro-properties are imposed on said reference speech signal.

5. A method according to claim 4, wherein said macro-properties are imposed on said output speech signal prior to said perceptual approximation.

6. A method according to claim 4, wherein said macro-properties are imposed on said output speech signal during said perceptual approximation.

7. A method according to claim 4, wherein said macro-properties are imposed on said output speech signal after said perceptual approximation.

8. A method according to claim 1, 2 or 3, wherein macro-properties are retrieved representative of said output speech signal, and wherein said macro-properties are imposed on said output speech signal prior to said comparison.

9. A method according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein said comparison comprises calculation of perceptual distance between said output speech signal and said reference signal.

10. A method according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9 wherein said output speech signal is subjected to time/frequency-domain transformation, and wherein said reference speech signal is retrieved from said transformed output speech signal.

21. Use of the method and device according to any of the previous claims for assessing speech quality of an output speech signal in an IP (Internet Protocol) based telecommunications network.

22. Use of the method and device according to claim 21, wherein said telecommunications network is a wireless IP telecommunications network.

23. Use of the method and device according to claim 21 or 22 for controlling speech quality in said telecommunications network.

11. A device for output based objective speech quality assessment, comprising retrieval means operatively connected for retrieving a reference signal from a degraded output speech signal comprising a speech information portion and comparator means operatively connected for comparing said output speech signal with said reference signal, characterized in that said retrieval means comprise processing means operatively connected for perceptual approximation of said speech information portion of said output speech signal using a speech recoder producing a reference speech signal of finite bitrate.

12. A device according to claim 11, wherein said retrieval means comprise a reference speech codec as a speech recoder for providing said reference speech signal by recoding of said output speech signal.

13. A device according to claim 11 or 12, wherein said speech recoder is of a type that is essentially transparent for clean, undistorted speech signals and essentially non-transparent for distorted speech signals in a degree that is a measure of the distortedness of said speech signal.

14. A device according to claim 11, 12 or 13, comprising means operatively connected for retrieving macro-properties representative of said output speech signal, and superposition means for imposing said macro-properties on said reference signal.

15. A device according to claim 14, wherein said superposition means are operatively connected for imposing said macro-properties on said output speech signal prior to said perceptual approximation.

16. A device according to claim 14, wherein said superposition means are operatively connected for imposing said macro-properties on said output speech signal via said processing means operative for perceptual approximation of said output signal.

17. A device according to claim 14, wherein said superposition means are operatively connected for imposing said macro-properties on said output speech signal after said perceptual approximation thereof.

18. A device according to claim 14, wherein said superposition means are operatively connected for imposing said macro-properties on said output speed signal prior to comparison thereof.

19. A device according to claim 11, 12, 13, 14, 15, 16, 17 or 18, wherein said comparison means are operatively connected for calculating perceptual distance between said output speech signal and said reference signal.

20. A device according to claim 11, 12, 13, 14, 15, 16, 17, 18 or 19, comprising transformation means for time/frequency-domain transformation of said output speech signal, and wherein said retrieval means are operatively connected for retrieving said reference speech signal from said transformed output speech signal.