1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T P.563 TELECOMMUNICATION (05/2004) STANDARDIZATION SECTOR OF ITU SERIES P: TELEPHONE TRANSMISSION QUALITY, TELEPHONE INSTALLATIONS, LOCAL LINE NETWORKS Objective measuring apparatus Single-ended method for objective speech quality assessment in narrow-band
2、 telephony applications Notice to Subscribers of ITU-T Recommendation P.563: To obtain one complimentary CD-ROM containing ITU-T Recommendation P.563 and the Reference Implementation and Conformance Data, please contact IHS/Retail at 1-800-854-7179. INTERNATIONAL TELECOMMUNICATION UNION ITU-T P.563T
3、ELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2004) SERIES P: TELEPHONE TRANSMISSION QUALITY, TELEPHONE INSTALLATIONS, LOCAL LINE NETWORKS Objective measuring apparatus Single-ended method for objective speech quality assessment in narrow-band telephony applications ITU-T Recommendation P.563 I
4、TU-T P-SERIES RECOMMENDATIONS TELEPHONE TRANSMISSION QUALITY, TELEPHONE INSTALLATIONS, LOCAL LINE NETWORKS Vocabulary and effects of transmission parameters on customer opinion of transmission quality Series P.10 Subscribers lines and sets Series P.30 P.300 Transmission standards Series P.40 Objecti
5、ve measuring apparatus Series P.50 P.500 Objective electro-acoustical measurements Series P.60 Measurements related to speech loudness Series P.70 Methods for objective and subjective assessment of quality Series P.80 P.800 Audiovisual quality in multimedia services Series P.900 For further details,
6、 please refer to the list of ITU-T Recommendations. ITU-T Rec. P.563 (05/2004) i ITU-T Recommendation P.563 Single-ended method for objective speech quality assessment in narrow-band telephony applications Summary This Recommendation describes an objective single-ended method for predicting the subj
7、ective quality of 3.1 kHz (narrow-band) telephony applications. This Recommendation presents a high-level description of the method and advice on how to use it. An ANSI-C reference implementation, described in Annex A, is provided in separate files and forms an integral part of this Recommendation.
8、A conformance testing procedure is also specified in Annex A to allow a user to validate that an alternative implementation of the model is correct. This ANSI-C reference implementation shall take precedence in case of conflicts between the high-level description as given in this Recommendation and
9、the ANSI-C reference implementation. This Recommendation includes an electronic attachment containing an ANSI-C reference implementation and conformance testing data. Source ITU-T Recommendation P.563 was approved on 14 May 2004 by ITU-T Study Group 12 (2001-2004) under the ITU-T Recommendation A.8
10、procedure. ii ITU-T Rec. P.563 (05/2004) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying techn
11、ical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which,
12、in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC
13、. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ens
14、ure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does
15、not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning
16、the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, whi
17、ch may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2005 All rights reserved. No part of this publication may be reproduced, by any means w
18、hatsoever, without the prior written permission of ITU. ITU-T Rec. P.563 (05/2004) iii CONTENTS Page 1 Introduction 1 2 Normative references 1 3 Abbreviations 2 4 Scope 2 5 Convention 5 6 Requirements on speech signals to be assessed 5 7 Overview of P.563 6 7.1 Vocal tract analysis and unnaturalness
19、 of speech. 7 7.2 Analysis of strong additional noise 8 7.3 Interruptions, mutes and time clipping. 8 7.4 Distortion classification 8 8 Comparison between objective and subjective scores 9 8.1 Correlation coefficient 10 9 High level description of the functional blocks used in P.563 . 10 9.1 Descrip
20、tion of basic speech descriptors and the signal pre-processing 10 9.2 Description of the functional block Vocal tract analysis and Unnatural Voice 18 9.3 Description of the functional block Additive Noise . 32 9.4 Description of the Mutes/Interruptions functional block components 42 9.5 Description
21、of the Speech Quality Model 46 Annex A Source code for reference implementation and conformance tests. 49 A.1 List of files provided for the ANSI-C reference implementation. 49 A.2 List of files provided for conformance validation 50 A.3 Speech files provided for validation with variable delay . 57
22、A.4 Conformance data sets 57 A.5 Conformance requirements 57 A.6 Conformance test on unknown data . 57 Electronic attachment: ANSI-C reference implementation and conformance testing data. ITU-T Rec. P.563 (05/2004) 1 ITU-T Recommendation P.563 Single-ended method for objective speech quality assessm
23、ent in narrow-band telephony applications11 Introduction The P.563 algorithm is applicable for speech quality predictions without a separate reference signal. For this reason, this method is recommended for non-intrusive speech quality assessment, live network monitoring and assessment by using unkn
24、own speech sources at the far-end side of a telephone connection. Real systems may include background noise, filtering and variable delay, as well as distortions due to channel errors and speech codecs. Up to now, methods for speech quality assessment of such systems, such as ITU-T Rec. P.862, requi
25、re either a reference signal or they calculate only quality indexes based on a restricted set of parameters like level, noise in speech pauses and echoes. The P.563 approach is the first recommended method for single-ended non-intrusive measurement applications that takes into account the full range
26、 of distortions occurring in public switched telephone networks and that is able to predict the speech quality on a perception-based scale MOS-LQO according to ITU-T Rec. P.800.1. This Recommendation is not restricted to end-to-end measurements; it can be used at any arbitrary location in the transm
27、ission chain. The calculated score is then comparable to the quality perceived by a human listener, who is listening with a conventional shaped handset at this point. The validation of P.563 included all available experiments from the former P.862 validation process, as well as a number of experimen
28、ts that specifically tested its performance by using an acoustical interface in a real terminal at the sending side. Furthermore, the P.563 algorithm was tested independently with unknown speech material by third party laboratories under strictly defined requirements. It is recommended that P.563 be
29、 used for speech quality assessment in 3.1 kHz (narrow-band) telephony applications only. 2 Normative references The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication
30、, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the curr
31、ently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation P.48 (1988), Specification for an intermediate reference system. ITU-T Recommendation P.8
32、00 (1996), Methods for subjective determination of transmission quality. ITU-T Recommendation P.810 (1996), Modulated noise reference unit (MNRU). _ 1This Recommendation includes an electronic attachment containing an ANSI-C reference implementation and conformance testing data. 2 ITU-T Rec. P.563 (
33、05/2004) ITU-T Recommendation P.830 (1996), Subjective performance assessment of telephone-band and wideband digital codecs. ITU-T Recommendation P.862 (2001), Perceptual evaluation of speech quality (PESQ): An objective method for end-to-end speech quality assessment of narrow-band telephone networ
34、ks and speech codecs. ITU-T P-series Recommendations Supplement 23 (1998), ITU-T coded-speech database. 3 Abbreviations This Recommendation uses the following abbreviations: ACR Absolute Category Rating CELP Code-Excited Linear Prediction dBov dB to overload point DCME Digital Circuit Multiplication
35、 Equipment ERP Ear Reference Point HATS Head and Torso Simulator IRS Intermediate Reference System LPC Linear Prediction Coefficient MOS Mean Opinion Score MOS-LQO Mean Opinion Score Listening Quality Objective MOS-LQS Mean Opinion Score Listening Quality Subjective PCM Pulse Code Modulation SNR Sig
36、nal-to-Noise Ratio SPL Sound Pressure Level 4 Scope Based on the benchmark results presented within Study Group 12 in 2003, an overview of the test factors, coding technologies and applications to which this Recommendation applies is given in Tables 1 to 3. Table 1 presents the relationships of test
37、 factors, coding technologies and applications for which this Recommendation has been found to show acceptable accuracy. Table 2 presents a list of conditions for which the Recommendation is known to provide inaccurate predictions or is otherwise not intended to be used. Finally, Table 3 lists facto
38、rs, technologies and applications for which P.563 has not currently been validated. Although correlations between objective and subjective scores in the benchmark were around 0.89 for both known and unknown data, the P.563 algorithm cannot be used to replace subjective testing but it can be applied
39、for measurements where auditory tests would be too expensive or not applicable at all. It should also be noted that the P.563 algorithm does not provide a comprehensive evaluation of transmission quality. It only measures the effects of one-way speech distortion and noise on speech quality in the sa
40、me way as it can be investigated by an auditory test assessing listening quality on an ACR scale. The P.563 algorithm scores the speech signal in that way, as it is presented to a human listener by using a conventional shaped handset and listening with a SPL of 79 dB at the ERP. ITU-T Rec. P.563 (05
41、/2004) 3 Because P.563 models the human quality perception in combination with a common receiving terminal, the degradation produced by a receiving terminal and other equipment in a real monitored connection, which are connected behind the measurement point, cannot be taken into account. Because P.5
42、63 predicts listening quality scores, all effects degrading talking quality or conversational quality only cannot be taken into account. That means, the effects of loudness loss, delay, sidetone, talker-echo, and other impairments related to the talking quality or two-way interaction only are not re
43、flected in the P.563 scores. Therefore, it is possible to have high P.563 scores, yet non-optimal quality of the connection overall. It should be highlighted that P.563 is designed for the prediction of speech quality in public switched narrow-band telephone networks. The types and the amount of the
44、 distortions, technologies and applications in the validation procedure cover the range of common occurrences in such networks. Extreme situations, even if they fulfil the terms of Table 1, may be predicted inaccurately. Table 1/P.563 Factors for which P.563 had demonstrated acceptable accuracy and
45、recommended application scenarios Test factors Characteristics of the acoustical environment (reflections, different reverberation times) as used in the validation phase. Mobile and conventional shaped handsets as well as handsfree terminals according to P.340 test-setup in office environments were
46、used (See Note). Environmental noise at the sending side Characteristics of the acoustical interface of the sending terminal Remaining electrical and encoding characteristics of the sending terminal Speech input levels to a codec Transmission channel errors Packet loss and packet loss concealment wi
47、th CELP codecs Bit rates if a codec has more than one bit-rate mode Transcodings Effect of varying delay on listening quality in ACR tests Short-term time warping of speech signal Long-term time warping of speech signal Transmission systems including echo cancellers and noise reduction systems under
48、 single talk conditions and as they will be scored on an ACR scale Coding technologies Waveform codecs, e.g., G.711; G.726; G.727 CELP and hybrid codecs 4 kbit/s, e.g., G.728, G.729, G.723.1 Other codecs: GSM-FR, GSM-HR, GSM-EFR, GSM-AMR, CDMA-EVRC, TDMA-ACELP, TDMA-VSELP, TETRA 4 ITU-T Rec. P.563 (
49、05/2004) Table 1/P.563 Factors for which P.563 had demonstrated acceptable accuracy and recommended application scenarios Recommended application scenarios for P.563 Live network monitoring using digital or analogue connection to the network Live network end-to-end testing using digital or analogue connection to the network Live network end-to-end testing with unknown speech sources at the far end side NOTE For more detailed information, please refer to the published testplans (“Joint Test Plan for Single-Ended Assessment Models“,
