ITU-T HDBK T-1992 Handbook on Telephonometry《通话时计手册》.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE HANDBOOK ON TELEPHONOMETRY Geneva, 1992 ISBN 92-61 -0491 1-7 O U 1993 All rights reserved. No part of this publication may be reproduced or utilised in any form or by any means, electronic or

2、 mechanical, including photocopying and microfilm, without written permission from the U. CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SECTION 1 - General . . 1.1.1 Definition of terms of telephony and telephonometry . 1.1.2 Units and quantities

3、1.2 Notes on artificial lines, feed circuits and similar ancillary laboratory equipment 1.2.1 Artificial lines . 1.2.2 Feeding bridges 1.2.3 1.3 Basic concepts of statistics Circuit for measuring the transmission characteristics of a telephone set 1.3.1 Definitions of g . 1.3.3 Accuracy, reliability

4、, validity . 1.3.4 Statistical analysis and treatmen . Appendix (to 3 1.3.4) -Analysis of the results of a determination of reference equivalent 1.4.1 Orthoreference c . 1.4.2 1.4.3 1.4 Orthotelephonic responses Transformation from ear reference point (ERP) to ear-drum reference point (DRP) Conversi

5、on of the orthoreference response to the ERP of the listener . . . . . . . . . . . 1.4.4 Applied telephone connection and orthotelephonic response . 1.4.6 Receive measurements . SECTION 2 - Subjective tests 2.0 2.1 2.2 2.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6、 . . . . efinition of a speech link . 2.0.2 Classifications and choice of assessment methods . 2.1.3 2.1.4 SETED Working Standard 2.1.5 Intermediate Reference System (IRS) Reference Equivalents, R25 Equivalents and Corrected Reference Equivalents . . . . . . . . . . . . . . . . . . . . 2.2.1 Introdu

7、ction 2.2.2 2.2.3 Techniques 2.2.4 2.2.5 NOSFER (nouveau systme fondamental pour la dtermination des quivalents de . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Essential test arrangements for use with a reference system Junction Arrangement . . . . . . . .

8、. . . . . . . . . . . . . . . . . . . . . . . . R25 Equivalents and Corrected Reference Equivalents (CRE) Introduction and background on the development of Loudness Ratings Some disadvantages of Reference Equivalents (RE) Corrected Reference Equivalents (CRE) Determination of LR . . . . . . . . . .

9、. . . . . . . . . . . . . . . . . . . . . Loudness Ratings . . . . . . . . . . . . . . . . . . . . . 2.3.1 2.3.2 2.3.3 2.3.4 Loudness Ratings (LR) . 2.3.5 2.3.6 Sidetone . Annex A (to 3 2.3) - Advantages of Loudness Rating Handbook on Telephonometry (1992) Page 1 2 2 2 2 3 3 3 9 9 9 11 12 13 17 21 2

10、1 21 24 26 28 30 35 35 35 37 38 39 40 42 44 45 47 47 47 52 54 55 55 55 56 57 57 59 62 65 1 2.4 Speech intelligibility measurement methods . 2.4.1 General . 2.4.2 Articulation method . 2.4.3 Method for determining the articulation reference equivalent ( 2.4.4 Selection methods (multiple choice tests)

11、 . 2.4.5 Repetition observation tests . 2.4.6 2.4.7 Comparison of methods . Annex A (to 3 2.4) - Description of the ARAEN Composition of ARAEN . Conversation methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A. 1 A.2 Transmission path . A.3 Theoretical e

12、ffic Annex B (to 3 2.4) - Articulatio B. 1 B.2 2.5 2.6 SECTION 3 3.0 3.1 3.2 3.3 Definition of the articulation reference equivalent (AEN) . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . Determination of AEN . . . . . . . . Opinion tests . . . . . . . . . . . . . .

13、. . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5.1 General . 2.5.3 2.5.4 CCT Recommendations . . Utilization of the outcome of experiments . . . . . . . . . . . . . . . . . . . . . 2.5.5 The continuing need for subjective tests . 2.5.6 Conversational or listening tests . 2.5.7 2.5.8 2.5.9 2

14、.6.1 General . . 2.6.3 Application . Objective measurement Introductioii to objective . Notes on electro-acoustic measuring techniques 3.1.1 Introduction . 3.1.2 Noise . 3.1.4 Terminations Laboratory or field tests . General rules and precautions . Analysis of results of opinion tests . . . . 3.2.1

15、General . 3.2.4 Artificial ears . 3.2.5 Artificial voice . Measurements on complete handset telephones . . . . 3.3.0 Introduction . 3.3.2 Measuring the receiving sensitivity of a local telephone system, Sje 3.3.5 3.3.6 3.3.7 Measuring the 600 ohm sending sensitivity of a telephone instrument, SS600

16、Measuring the matched receiving sensitivity of a telephone set, SR Measuring the 600 ohm receiving sensitivity of a telephone set, SR600 Page 66 66 67 76 76 78 78 79 81 81 82 82 86 86 86 86 86 88 89 90 90 90 91 91 110 115 115 115 120 122 122 122 122 122 123 1 24 1 24 125 126 126 126 127 130 131 133

17、133 133 135 136 137 140 141 142 11 Handbook on Telephonometry (1992) 3.3.8 3.3.9 3.3.10 3.3.11 3.3.12 3.3.13 3.3.14 3.3.15 3.3.16 3.3.17 3.3.18 3.3.19 3.3.20 Measuring the terminal impedance of a telephone set, Zc Measurement of minimum sidetone impedance, Zso . Determination of return loss and bala

18、n Measurement of impedance balance about Measurement of signal balance about earth . Measurement of sending harmonic distortion of a loc Measuring the receiving harmonic distortion of a 1 Measurement of receiving noise of a telep Measurement of room noise sending sensitivity and the determination of

19、 ASM Measurement of receive acoustic limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Measuring the room noise sidetone sensitivity, Smesr, for a local telephone system Measurements on digital handset telephones . . . . . . . . . . . telephone system (LTS) Measu

20、rement of sending noise of a local telephone system (DELSM) for an LTS Appendix I (to 3 3.3) - Hybrid circuit . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I. 1 1.2 3.4 3.5 3.6 Transformer specificati

21、on Hybrid circuit connections . . . . . . . . . . . . . . . . Measurements on headsets . . . . . . . . . . . . . 3.4.0 Introduction 3.4.1 Definition of a headset . . 3.4.3 Basic testing ph 3.4.4 3.4.5 3.4.6 3.4.2 Elements of the testing method . 4-wire to 2-wire coupling networks Types of headset mi

22、crophones used . Positioning the headset microphone to real and artificial mouths 3.4.7 Types of headset receiver systems 3.4.8 Coupling the he 3.4.9 Precautions in testing of headsets . Measurements on hands-free telephones 3.5.1 The performance of HF telephones . 3.5.2 Test arrangements . 3.5.3 Me

23、asuring sensitivity 3.5.5 Measuring switching times . 3.5.4 Measuring frequency sensitivity response curves . . . . . . Measurements on transducers and other acoustic components 3.6.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . .

24、 . . . . . . . . . . . . . . 3.6.1 Measuring the sensitivity of an earphone, S, 3.6.2 Measuring the sensitivity of a microphone, S . 3.6.3 Measuring the s 3.6.4 3.6.5 3.6.7 3.6.8 3.6.9 Measuring the equivalent (or talking) resistance of a carbon microphone, RT . Measuring the dynamic resistance of a

25、 carbon microphone, RD Measuring the acoustic stability margin for a telephone handset and associated telephone speech circuit . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . Measuring the sensitivity and modulus of impedance Measurement of bell ringerhone ringer sound spectrum and sou

26、nd output . . . . . . 3.6.6 Measurement of Terminal Coupling Loss (TCL) ringer Appendix I (to 3 3.6) - A transportable reverberation box for measurement of total sound power radiated by telephone sounders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7 Speech measuring appara

27、tus 3.7.1 Introduction 3.7.2 Characteristics of speech wav . 3.7.3 Speech volume measuring equipment . Handbook on Telephonometry (1992) Page 143 144 146 148 149 149 15 1 152 154 156 159 161 162 163 163 164 164 164 164 164 165 166 167 168 169 169 170 170 17 1 173 175 176 176 179 179 180 181 182 186

28、187 189 192 194 195 200 20 1 20 1 20 1 203 . 111 3.7.4 Speech volume meters 3.7.5 The digital speech voltmeter . objective characteristics . . . . . 3.9.1 Introduction . . 3.9.2 Performance requirements . Appendix I (to 3 3.9) - Typical telephone set parameters . having this facility. . SECTION 4 -

29、Calculations based on objective characteristics . 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 Loudness rating calculations . . 4.1.1 Background . 4.1.2 General explanations of loudness rating terms . 4.1.3 Psycho-acoustic model for loudness ratings Calculation of loudness ratings . . . . . . . . . . .

30、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.1 Calculation of sending loudness rating . . Loudness ratings of telephone sets as used in transmission planning 4.4.1 General remarks 4.4.2 Normal speech transmission . 4.4.4 Echo and crosstalk . . Some useful transmissio

31、n form . 4.5.1 General . 4.5.2 4.5.3 The 2-wirel4-wire hybrid 4.5.5 4.6.1 Background 4.6.3 Calculation of sound articulation . Opinion models and their use in transmission performance assessment. 4.8.1 General 4.8.3 4.8.4 Comparison of models . 4.8.5 Present state of the art . 4.8.6 A possible futur

32、e direc 4.9.1 Measu ger acoustic spectrum The general chain matrix equation . 4.5.4 The 2-wirel4-wirel2-wire loop . The minimum balance return 1 . Structure of an opinion model . . . Calculation of Weighted Terminal Coupling Loss . Page 204 205 208 212 213 213 213 2 14 216 216 218 219 220 220 220 22

33、 1 22 1 223 224 225 226 227 229 230 230 230 232 234 237 237 237 24 1 244 246 255 255 256 25 8 262 263 263 264 264 264 264 264 265 265 266 269 iv Handbook on Telephonometry (1992) Page 27 1 27 1 27 1 272 273 SECTION 5 - 5.1 5.2 5.3 5.4 Instrumentation for the objective assessment of loudness related

34、ratings Loudness loss units Instrumentation . Descriptions of new automatic test equipment 5.4.1 CERF - equipment for the objective measuremen 5.4.2 AURAL (Automatic Speech Quality Rating System based on Loudness) - NTT 5.4.3 TIGGER - an automatic test system designed and used by BT and the United K

35、ingdom 5.4.4 Loudness rating meter . 5.4.5 Sweeping-frequency he determination of loudness rating for evaluating the transmission performance parameters of handset telephones . 274 277 28 1 283 287 Handbook on Telephonometry (1992) V FOREWORD The VIIth Plenary Assembly of the CCT in 1980 charged Stu

36、dy Group Xi with the task of preparing a ?Handbook on Telephonometry?. This was duly studied in the period 198 1-1984, with the Handbook becoming available in 1987. Since the inputs into the Handbook only reflected the Recommendations up to 1984, and since 1984 most of the Recommendations in the P-S

37、eries have been updated and there have also been several new Recommendations, it was decided in 1988 to produce a second edition by the end of the 1989-1992 study period. The primary aims of the Handbook were to describe: - - objective measurement techniques; - Obviously, the Handbook is closely rel

38、ated with most of the P-Series Recommendations and may be considered to form a commentary to these Recommendations. In preparing this edition, close cooperation existed with the CCITT/Study Group XIISpeech quality Experts Group who were harmonizing the P.70 and P.80 Series of Recommendations. It wil

39、l be noticed, for example, in Recommendation P.80 - ?Methods for the Subjective Determination of Transmission Quality? - that there is frequent reference to this Handbook. Although, basically, the Handbook is intended to be a practical manual and the methods described in the Handbook should be consi

40、dered as a guide to sound engineering practice, it has been considered useful to include passages of textbook nature to help in understanding the underlying principles. The Handbook has attempted to resist the inclusion of too many obsolete Recommendations. It is hoped that the Handbook will still s

41、erve the needs of the developing countries as initially intended, but it may also be a guide for technical personnel on different educational levels in any country. In addition, it may pave the way for further international standardization of all kinds of telephonometric measurements. Remark the mai

42、n methods of subjective measurement; calculation techniques for estimating transmission performance. The methods described in the Handbook represent only what is considered as sound practice. CCT Recommendations should be given priority every time they exist. The reader is invited to refer to the mo

43、st recent amendments of the Recommendations. Furthermore, the length of the sections should not be considered as reflecting the importance of the subjects treated. At the 1988 Plenary Assembly in Melbourne the decision was taken to close the CCT laboratory. Acknowledgements Particular thanks must be

44、 given to the Administrations that have hosted the Rapporteurs? Group, namely: CSELT, CNET, AT Chapter 722 of the International Electrotechnical Vocabulary (published by IEC). 1.1.2 Units and quantities The following International Standards describe units, quantities, preferred values or expressions

45、 of magnitudes used in acoustics: IS0 31/7 IS0 1683 IS0 13 1 IS0 266 Various kinds of levels expressed in decibels have become common for acoustic measurements. A reference quantity is needed for each kind of level. Quantities and units of acoustics Preferred reference quantities for acoustic levels

46、 Expression of physical and subjective magnitudes of sound or noise in air Preferred frequencies for measurements. For several kinds of level, different reference quantities have been used from time to time. Thus, for clarity, it is necessary to indicate which reference quantity is being employed. I

47、t is recommended in IS0 131 that data on the physical magnitude of sound or noise be expressed by a statement of the soundpressure level measured at a particular point. The sound pressure level, Lp, expressed in decibels, of a sound or noise is given by the formula 20 log /PO), where p is the root-m

48、ean-square (RMS) value of sound pressure measured at a particular point, and po is the reference sound pressure. The preferred reference quantity for measurements of sound pressure in air is (according to ISO) po = 20 pPa. However, in electro-acoustics and in particular in telephonometry, where ofte

49、n sensitivities expressed as ratios between sound pressure and voltage (or vice versa) are used, the use of 1 Pa as reference sound pressure may be more convenient. A reference quantity may be introduced by re, which indicates that the level is “with reference to”, and may so be read. For example, “the sound pressure level, re 20 pPa, is equal to 80 dB”. Generally, if no reference quantity is given, it is assumed that sound pressure levels are given re 20 pPa. Therefore, if the reference quantity is 1 Pa, this should always be indicated. A practical way of designation, w