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Perceptual Evaluation of Speech Quality (PESQ)

Perceptual Evaluation of Speech Quality (PESQ). Speaker: Wen-Jen Lin Date: Dec. 3 2009. Outline. Introduction ITU-T P.862 P.862.3 P.862.2 P.862.1 P.862 - Overview of the basic philosophy used in PESQ Conclusion Experience Demo PESQ program Reference. Introduction.

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Perceptual Evaluation of Speech Quality (PESQ)

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  1. Perceptual Evaluation of Speech Quality (PESQ) Speaker: Wen-Jen Lin Date: Dec. 3 2009

  2. Outline • Introduction • ITU-T P.862 • P.862.3 • P.862.2 • P.862.1 • P.862 - Overview of the basic philosophy used in PESQ • Conclusion • Experience • Demo PESQ program • Reference

  3. Introduction • Classic Quality Measurement • Noise Ratio • Frequency Response Functions etc. • Speech coding ( ETSI GSM EFR/AMR, ITU-T G.728/729/723.1 etc) • New types of distortions • Voice over IP (packet loss and variable delay) • Voice over ATM (cell loss) • Voice over mobile (GSM, UMTS, frame repeat, front end clipping, comfort noise generation)

  4. Introduction (cont.) • PSQM (Perceptual Speech Qualify Measure) • P.861 - The first international standard for the perceptual quality measurement of telephone-band (300-3400 Hz) speech signals. • The scope of recommendation P.861 was limited to the assessment of telephone-band speech codecs only.

  5. ITU-T P.862 • P.862 • Perceptual evaluation of speech quality (PESQ): An objective method for end-to-end speech quality assessment of narrow-band telephone networks and speech codecs • Amendment 2 • P.862.1 • Mapping function for transforming P.862 raw result scores to MOS-LQO • P.862.2 • Wideband extension to Recommendation P.862 for the assessment of wideband telephone networks and speech codecs • P.862.3 • Application guide for objective quality measurement based on Recommendations P.862, P.862.1 and P.862.2

  6. Application • P.862.3 – Example of measurement set-up and terminology

  7. P.862.1 • MOS-LQO (P.800.1) • ITU-T Rec. P.862 provides raw scores in the range –0.5 to 4.5. • The mapping function:

  8. Figure of Mapping Function

  9. P.862 - Overview of the basic philosophy used in PESQ

  10. P.862 - Overview of the basic philosophy used in PESQ (cont.)

  11. Addition of background noise

  12. Factors for which PESQ had demonstrated acceptable accuracy • Speech input levels to a codec • Errors in the transmission channel between an encoder and a decoder • Bit rates if a codec has more than one bit-rate mode • Transcodings • Environmental noise in the sending side

  13. PESQ is not intended to be used to assess • Effect of listening level • Conversational delay • Talker echo, where a subjects hears his own voice delayed • Talker sidetone, where a subjects may hear its own voice distorted • Non-intrusive measurements, where only output signals are available from the system music

  14. which PESQ has not currently been validated

  15. Conclusion • PESQ has been evaluated on a very wide range of speech codecs and telephone network tests. • It has been found to produce accurate predictions of quality in the presence of diverse end-to-end network behaviors. • PESQ represents a significant step forward in the accuracy and range of applicability of objective speech quality assessment methods.

  16. Head and Torso Simulator(HATS)

  17. Spirent Abacus

  18. Abacus Control GUI

  19. Testbed DSLAIIHandset Interface ControllerMalden

  20. RTP Flow

  21. Demo PESQ program

  22. Reference • HATS - http://www.bksv.com/doc/bp2240.pdf • ITU-T Rec. P.862, “Perceptual Evaluation of Speech Quality (PESQ), an Objective Method for End-to-end Speech Quality Assessment of Narrowband Telephone Networks and Speech Codecs”, International Telecommunication Union, Geneva, Switzerland (2001 Feb.) • Malden - http://www.malden.co.uk/dsla.htm • Perceptual Evaluation of Speech Quality (PESQ), the new ITU standard for end-to-end speech quality assessment. Part II – Psychoacoustic model - http://www.mp3-tech.org/programmer/docs/2001-P03b.pdf • Spirent - http://www.spirent.com/

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