1 TAC2000/ IP Telephony Lab Perceptual Evaluation of Speech Quality (PESQ) Speaker: Wen-Jen Lin Date: Dec

2 TAC2000/ IP Telephony Lab Outline  Introduction  ITU-T P.862  P  P  P  P Overview of the basic philosophy used in PESQ  Conclusion  Experience  Demo PESQ program  Reference

3 TAC2000/ IP Telephony Lab Introduction  Classic Quality Measurement Noise Ratio Noise Ratio Frequency Response Functions etc. Frequency Response Functions etc. Speech coding ( ETSI GSM EFR/AMR, ITU-T G.728/729/723.1 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 IP (packet loss and variable delay) Voice over ATM (cell loss) Voice over ATM (cell loss) Voice over mobile (GSM, UMTS, frame repeat, front end clipping, comfort noise generation) Voice over mobile (GSM, UMTS, frame repeat, front end clipping, comfort noise generation)

4 TAC2000/ IP Telephony Lab Introduction (cont.)  PSQM (Perceptual Speech Qualify Measure) P The first international standard for the perceptual quality measurement of telephone- band ( Hz) speech signals. P The first international standard for the perceptual quality measurement of telephone- band ( Hz) speech signals. The scope of recommendation P.861 was limited to the assessment of telephone-band speech codecs only. The scope of recommendation P.861 was limited to the assessment of telephone-band speech codecs only.

5 TAC2000/ IP Telephony Lab 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 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 Amendment 2  P Mapping function for transforming P.862 raw result scores to MOS-LQO Mapping function for transforming P.862 raw result scores to MOS-LQO  P Wideband extension to Recommendation P.862 for the assessment of wideband telephone networks and speech codecs Wideband extension to Recommendation P.862 for the assessment of wideband telephone networks and speech codecs  P Application guide for objective quality measurement based on Recommendations P.862, P and P Application guide for objective quality measurement based on Recommendations P.862, P and P.862.2

6 TAC2000/ IP Telephony Lab Application  P – Example of measurement set-up and terminology

7 TAC2000/ IP Telephony Lab P  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 TAC2000/ IP Telephony Lab Figure of Mapping Function

9 TAC2000/ IP Telephony Lab P Overview of the basic philosophy used in PESQ

10 TAC2000/ IP Telephony Lab P Overview of the basic philosophy used in PESQ (cont.)

11 TAC2000/ IP Telephony Lab Addition of background noise

12 TAC2000/ IP Telephony Lab 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 TAC2000/ IP Telephony Lab 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 TAC2000/ IP Telephony Lab which PESQ has not currently been validated

15 TAC2000/ IP Telephony Lab 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 TAC2000/ IP Telephony Lab Head and Torso Simulator(HATS)

17 TAC2000/ IP Telephony Lab Spirent Abacus

18 TAC2000/ IP Telephony Lab Abacus Control GUI

19 TAC2000/ IP Telephony Lab Testbed DSLAII Handset Interface Controller Malden

20 TAC2000/ IP Telephony Lab RTP Flow

21 TAC2000/ IP Telephony Lab Demo PESQ program

22 TAC2000/ IP Telephony Lab Reference  HATS  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 -  Perceptual Evaluation of Speech Quality (PESQ), the new ITU standard for end-to-end speech quality assessment. Part II – Psychoacoustic model - tech.org/programmer/docs/2001-P03b.pdf tech.org/programmer/docs/2001-P03b.pdfhttp:// tech.org/programmer/docs/2001-P03b.pdf  Spirent -