PESQ

PESQ, Perceptual Evaluation of Speech Quality, is a family of standards comprising a test methodology for automated assessment of the speech quality as experienced by a user of a telephony system. It is standardised as ITU-T recommendation P.862 (02/01). Today, PESQ[1] is a worldwide applied industry standard for objective voice quality testing used by phone manufacturers, network equipment vendors and telecom operators. Its usage requires a license.

Measurement scope

PESQ was particularly developed to model subjective tests commonly used in telecommunications (e.g. ITU-T P.800) to assess the voice quality by human beings. Consequently, PESQ[1] employs true voice samples as test signals. In order to characterize the listening quality as perceived by users, it is of paramount importance to load modern telecom equipment with speech-like signals. Many systems are optimized for speech and would respond in an unpredictable way to non-speech signals (e.g. tones, noise). Guidelines for proper applications of voice test samples are defined in the PESQ application guide ITU-T P.862.3.

Genealogy of related standards

ITU-T’s family of full reference objective voice quality measurements started in 1997 with P.861 (PSQM), which was superseded by P.862 (PESQ)[1] in 2001. P.862 was later complemented with the recommendations P.862.1[2] (mapping of PESQ scores to a MOS scale), P.862.2[3] (wideband measurements) and P.862.3[4] (application guide). Since 2011 P.863 (POLQA)[5] is in force. Two additional implementer’s guides for P.863 have been consented by ITU-T Study Group 12 in November 2011. In addition to the above listed full reference methods, the list of ITU-T’s objective voice quality measurement standards also includes P.563[6] (no-reference algorithm).

Testing typology

Depending on the information that is made available to an algorithm, voice-quality test algorithms can be divided into two main categories:

PESQ is a full-reference algorithm and analyzes the speech signal sample-by-sample after a temporal alignment of corresponding excerpts of reference and test signal. PESQ[1] can be applied to provide an end-to-end (E2E) quality assessment for a network, or characterize individual network components.

PESQ results principally model mean opinion scores (MOS) that cover a scale from 1 (bad) to 5 (excellent). A mapping function to MOS-LQO is outlined under P.862.1.[2]

See also

References

  1. 1 2 3 4 http://www.itu.int/rec/T-REC-P.862/en ITU-T Recommendation 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
  2. 1 2 http://www.itu.int/rec/T-REC-P.862.1/en ITU-T Recommendation P.862.1: Mapping function for transforming P.862 raw result scores to MOS-LQO
  3. http://www.itu.int/rec/T-REC-P.862.2/en ITU-T Recommendation P.862.2: Wideband extension to Recommendation P.862 for the assessment of wideband telephone networks and speech codecs
  4. http://www.itu.int/rec/T-REC-P.862.3/en ITU-T Recommendation P.862.3 Application guide for objective quality measurement based on Recommendations P.862, P.862.1 and P.862.2
  5. http://www.itu.int/rec/T-REC-P.863/en ITU-T Recommendation P.863: Perceptual objective listening quality assessment
  6. 1 2 http://www.itu.int/rec/T-REC-P.563/en ITU-T Recommendation P.563: Single-ended method for objective speech quality assessment in narrow-band telephony applications

External links

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