PESQ
Encyclopedia
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 is a worldwide applied industry standard for objective voice quality testing used by phone manufacturers, network equipment vendors and telecom operators.
) in 2001. P.862 was later complemented with the recommendations P.862.1 (mapping of PESQ
scores to a MOS scale), P.862.2 (wideband measurements) and P.862.3 (application guide). Since 2011 P.863 (POLQA
) 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 (no-reference algorithm).
PESQ is full-reference algorithm and analyzes the speech signal sample-by-sample after a temporal alignment of corresponding excerpts of reference and test signal. PESQ 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 score
s (MOS) that cover a scale from 1 (bad) to 5 (excellent). A mapping function to MOS-LQO is outlined under P.862.1.
Telephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
system. It is standardised as ITU-T
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
recommendation P.862 (02/01). Today, PESQ is a worldwide applied industry standard for objective voice quality testing used by phone manufacturers, network equipment vendors and telecom operators.
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 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 (PESQPESQ
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...
) in 2001. P.862 was later complemented with the recommendations P.862.1 (mapping of PESQ
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...
scores to a MOS scale), P.862.2 (wideband measurements) and P.862.3 (application guide). Since 2011 P.863 (POLQA
POLQA
POLQA Perceptual Objective Listening Quality Assessment, also known as ITU-T Rec. P.863 is an ITU-T Standard that covers a model to predict speech quality by means of digital speech signal analysis.------------------ Measurement scope :...
) 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 (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:- A “Full Reference” (FR) algorithm has access to and makes use of the original reference signal for a comparison (i.e. a difference analysis). It can compare each sample of the reference signal (talker side) to each corresponding sample of the degraded signal (listener side). FR measurements deliver the highest accuracy and repeatability but can only be applied for dedicated tests in live networks (e.g. drive test tools for mobile network benchmarks).
- A “No Reference” (NR) algorithm only uses the degraded signal for the quality estimation and has no information of the original reference signal. NR algorithms (like e.g. P.563) are low accuracy estimates, only, as the originating voice characteristics (e.g. male or female talker, background noise, non-voice) of the source reference is completely unknown. A common variant of NR algorithms don't even analyze the decoded audio signal but work on an analysis of the digital bit stream on an IP packet level, only. The measurement is consequently limited to a transport stream analysis.
PESQ is full-reference algorithm and analyzes the speech signal sample-by-sample after a temporal alignment of corresponding excerpts of reference and test signal. PESQ 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 score
Mean Opinion Score
The Mean Opinion Score test has been used for decades in telephony networks to obtain the human user's view of the quality of the network. In multimedia especially when codecs are used to compress the bandwidth requirement , the mean opinion score ...
s (MOS) that cover a scale from 1 (bad) to 5 (excellent). A mapping function to MOS-LQO is outlined under P.862.1.
See also
- Perceptual Objective Listening Quality Assessment (POLQAPOLQAPOLQA Perceptual Objective Listening Quality Assessment, also known as ITU-T Rec. P.863 is an ITU-T Standard that covers a model to predict speech quality by means of digital speech signal analysis.------------------ Measurement scope :...
) - Perceptual Evaluation of Video Quality (PEVQPEVQPEVQ ' is a standardized end-to-end measurement algorithm to score the picture quality of a video presentation by means of a 5-point mean opinion score...
) - Perceptual Evaluation of Audio Quality (PEAQPEAQPEAQ is a standardized algorithm for objectively measuring perceived audio quality, developed in 1994-1998 by a joint venture of experts within Task Group 6Q of the International Telecommunication Union . It was originally released as ITU-R Recommendation BS.1387 in 1998 and last updated in 2001...
)
External links
- Official Website
- Official Website on POLQA
- Technical Information on PESQ
- http://www.malden.co.uk/pesq.htm Article on application of P.862
- http://www.microtronix.ca/pesq PESQ Measurement for VoIP and POTS telephones
- Application Note 1GA49: Psychoacoustic Audio Quality Measurements Using R&SUPV Audio Analyzer
- Application Note 1MA119: PESQ Measurement for GSM with R&SCMUgo
- Application Note 1MA136: PESQ Measurement for CDMA2000 with R&SCMUgo
- Application Note 1MA137: PESQ Measurement for WCDMA with R&SCMUgo
- Application Note 1MA149: VoIP Measurements for WiMAX