1、 IEC 60268-16 Edition 4.0 2011-06 INTERNATIONAL STANDARD NORME INTERNATIONALE Sound system equipment Part 16: Objective rating of speech intelligibility by speech transmission index Equipements pour systmes lectroacoustiques Partie 16: Evaluation objective de lintelligibilit de la parole au moyen de
2、 lindice de transmission de la parole IEC 60268-16:2011 THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2011 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, in
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16、 vous avez des questions, visitez le FAQ du Service clients ou contactez-nous: Email: csciec.ch Tl.: +41 22 919 02 11 Fax: +41 22 919 03 00 IEC 60268-16 Edition 4.0 2011-06 INTERNATIONAL STANDARD NORME INTERNATIONALE Sound system equipment Part 16: Objective rating of speech intelligibility by speec
17、h transmission index Equipements pour systmes lectroacoustiques Partie 16: Evaluation objective de lintelligibilit de la parole au moyen de lindice de transmission de la parole INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE XB ICS 33.160.01 PRICE CODE CODE PRIX
18、ISBN 978-2-88912-672-9 Registered trademark of the International Electrotechnical Commission Marque dpose de la Commission Electrotechnique Internationale 2 60268-16 IEC:2011 CONTENTS FOREWORD . 5 INTRODUCTION . 7 1 Scope . 9 2 Normative references . 9 3 Terms and definitions . 9 4 Description of th
19、e STI method 15 4.1 General . 15 4.1.1 Rationale for the STI method . 15 4.1.2 Applicability of the STI method 15 4.2 Background of the STI method 16 4.2.1 General . 16 4.2.2 Theoretical overview 17 4.2.3 Measurement of STI 18 4.3 Applicability of STI test methods . 19 4.4 Use of direct and indirect
20、 methods 20 4.5 Limitations of the STI method 21 4.5.1 General . 21 4.5.2 Frequency shifts 21 4.5.3 Centre clipping 22 4.5.4 Drop outs 22 4.5.5 Jitter 22 4.5.6 Vocoders . 22 4.5.7 Overestimation of STI under low background noise conditions . 22 4.5.8 Frequency response 22 4.5.9 Echoes 23 4.5.10 Fast
21、 amplitude compression and expansion . 23 4.5.11 Non-linear distortion 24 4.5.12 Impulsive and fluctuating noise 24 4.5.13 Hearing impaired listeners . 24 4.6 Conclusion 24 5 Direct method of measuring STI . 24 5.1 Overview . 24 5.2 STIPA . 25 5.3 Application 26 5.4 Limitations . 26 6 Indirect metho
22、d of measuring STI using the impulse response 26 6.1 Overview . 26 6.2 Application 27 6.3 Limitations (non-linear distortion) 28 7 Measurement procedures, post-processing of data and applications . 28 7.1 General . 28 7.2 Acoustical input . 28 7.3 Acoustical output . 30 7.4 Electrical input 30 7.5 E
23、lectrical output 30 7.6 Examples of input/output combinations 30 60268-16 IEC:2011 3 7.6.1 Acoustical input Acoustical output 30 7.6.2 Electrical input Electrical output (e.g. assessment of wired and wireless) communication systems) . 30 7.6.3 Acoustical input Electrical output (e.g. assessment of m
24、icrophones) . 31 7.6.4 Electrical input Acoustical output (e.g. assessment of PA systems) 31 7.7 Post-processing of measured MTF data 31 7.8 Issues concerning noise 31 7.8.1 General . 31 7.8.2 Measurement of background noise 32 7.8.3 Fluctuating noise . 32 7.9 Analysis and interpretation of the resu
25、lts . 32 7.10 Binaural STI measurements 33 8 Use of STI as a design prediction tool 33 8.1 Overview . 33 8.2 Statistical predictions 33 8.3 Prediction from simulated impulse response 34 Annex A (normative) Speech transmission index (STI) and revised STI methods . 35 Annex B (normative) STIPA method
26、 48 Annex C (normative) STITEL method . 49 Annex D (informative) RASTI method (obsolete) 50 Annex E (informative) Qualification of the STI and relationships with other speech intelligibility measures. 52 Annex F (informative) Nominal qualification bands for STI . 54 Annex G (informative) Examples o
27、f STI qualification bands and typical applications . 55 Annex H (informative) Non-native listeners 56 Annex I (informative) Effect of age-related hearing loss and hearing impairment on speech intelligibility. 57 Annex J (normative) Calibration of STI test signal level . 58 Annex K (informative) Exam
28、ple test report sheet for STI measurements 60 Annex L (normative) Prediction of STI using statistical methods 62 Annex M (informative) Adjustments to measured STI and STIPA results for simulation of occupancy noise and different speech levels 64 Annex N (informative) Other methods of determining spe
29、ech intelligibility 68 Bibliography 70 Figure 1 Concept of the reduction in modulation due to a transmission channel . 16 Figure 2 Modulation transfer function Input/output comparison 17 Figure A.1 Envelope function (panel A) of a 10 s speech signal for the 250 Hz octave band and corresponding envel
30、ope spectrum (panel B) . 36 Figure A.2 Theoretical expression of the MTF 37 Figure A.3 Measurement system and frequencies for the STI method 39 Figure A.4 Auditory masking of octave band (k 1) on octave band (k) . 40 Figure D.1 Illustration of a practical RASTI test signal . 51 Figure E.1 Relationsh
31、ips between some speech intelligibility measures 52 Figure E.2 Relationship between STI, speech intelligibility scores and listening difficulty ratings 34, 35 53 Figure F.1 STI qualification bands 54 4 60268-16 IEC:2011 Table 1 Comparison of STI test methods for different types of distortion 19 Tabl
32、e 2 Applicability of test 20 Table 3 Choice of method 21 Table A.1 Auditory masking as a function of the octave band level. 41 Table A.2 Absolute speech reception threshold level in octave bands 42 Table A.3 MTI octave band weighting factors . 42 Table A.4 Octave band levels (dB) relative to the A-w
33、eighted speech level 43 Table B.1 Modulation frequencies for the STIPA method 48 Table C.1 Modulation frequencies for the STITEL method 49 Table D.1 Modulation frequencies for the RASTI method . 50 Table E.1 Categories for listening difficulty 53 Table G.1 Examples between STI qualification bands an
34、d typical applications . 55 Table H.1 Adjusted intelligibility qualification tables for non-native listeners . 56 Table I.1 Adjusted intelligibility qualification tables for normal listeners and people over 60 years old with hearing loss . 57 Table M.1 Example calculation 64 60268-16 IEC:2011 5 INTE
35、RNATIONAL ELECTROTECHNICAL COMMISSION _ SOUND SYSTEM EQUIPMENT Part 16: Objective rating of speech intelligibility by speech transmission index FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical com
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45、ation. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all suc
46、h patent rights. International Standard IEC 60268-16 has been prepared by IEC technical committee 100: Multimedia equipment and systems. This fourth edition cancels and replaces the third edition, published in 2003, and constitutes a technical revision. This edition includes the following significan
47、t technical changes with respect to the previous edition: development of more comprehensive, complete and unambiguous standardization of the STI methodology; the term STI ris discontinued. A new function for the prediction of auditory masking effects is introduced; the concept of speech level and th
48、e setting of the level of the test signal have been introduced; 6 60268-16 IEC:2011 additional information has been included on prediction and measurement procedures. NOTE See Introduction for a historical summary referring to the various changes from the first to the fourth edition (current edition
49、). This bilingual version corresponds to the monolingual English version, published in 2011-06. The text of this standard is based on the following documents: FDIS Report on voting 100/1812/FDIS 100/1849/RVD Full information on the voting for the approval of this standard can be found in the report on voting indicated in the above table. The French version of this stand
