BS EN 60268-16:2011
$215.11
Sound system equipment – Objective rating of speech intelligibility by speech transmission index
| Published By | Publication Date | Number of Pages |
| BSI | 2011 | 78 |
This part of IEC 60268 specifies objective methods for rating the transmission quality of speech with respect to intelligibility.
The objective of this standard is to provide a comprehensive manual for all types of users of the STI method in the fields of audio, communications and acousti cs.
This standard does not provide STI criteria for certification of transmission channels (e.g . criteria for a voice-alarm system).
Three methods are presented, which are closely related and are referred to as STI, STIPA, and STITEL. The first two methods are intended for rating speech transmission performance with or without sound systems. The STITEL method has more restricted uses.
NOTE None of the methods are suitable for the measurement and assessment of speech privacy and speech masking systems , as STI has not been validated for conditions that represent speech privacy applications [1] 1.
The following information is included:
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measurement techniques ;
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prediction techniques.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 6 | CONTENTS |
| 9 | FOREWORD |
| 11 | INTRODUCTION |
| 13 | 1 Scope 2 Normative references 3 Terms and definitions |
| 19 | 4 Description of the STI method 4.1 General |
| 20 | 4.2 Background of the STI method Figures Figure 1 – Concept of the reduction in modulation due to a transmission channel |
| 21 | Figure 2 – Modulation transfer function – Input/output comparison |
| 23 | 4.3 Applicability of STI test methods Tables Table 1 – Comparison of STI test methods for different types of distortion |
| 24 | 4.4 Use of direct and indirect methods Table 2 – Applicability of test |
| 25 | 4.5 Limitations of the STI method Table 3 – Choice of method |
| 28 | 4.6 Conclusion 5 Direct method of measuring STI 5.1 Overview |
| 29 | 5.2 STIPA |
| 30 | 5.3 Application 5.4 Limitations 6 Indirect method of measuring STI using the impulse response 6.1 Overview |
| 31 | 6.2 Application |
| 32 | 6.3 Limitations (non-linear distortion) 7 Measurement procedures, post-processing of data and applications 7.1 General 7.2 Acoustical input |
| 34 | 7.3 Acoustical output 7.4 Electrical input 7.5 Electrical output 7.6 Examples of input/output combinations |
| 35 | 7.7 Post-processing of measured MTF data 7.8 Issues concerning noise |
| 36 | 7.9 Analysis and interpretation of the results |
| 37 | 7.10 Binaural STI measurements 8 Use of STI as a design prediction tool 8.1 Overview 8.2 Statistical predictions |
| 38 | 8.3 Prediction from simulated impulse response |
| 39 | Annex A (normative) Speech transmission index (STI) and revised STI methods Figure A.1 – Envelope function (panel A) of a 10 s speech signal for the 250 Hz octave band and corresponding envelope spectrum (panel B) |
| 40 | Figure A.2 – Theoretical expression of the MTF |
| 42 | Figure A.3 – Measurement system and frequencies for the STI method |
| 43 | Figure A.4 – Auditory masking of octave band (k – 1) on octave band (k) |
| 44 | Table A.1 – Auditory masking as a function of the octave band level |
| 45 | Table A.2 – Absolute speech reception threshold level in octave bands Table A.3 – MTI octave band weighting factors |
| 46 | Table A.4 – Octave band levels (dB) relative to the A-weighted speech level |
| 51 | Annex B (normative) STIPA method Table B.1 – Modulation frequencies for the STIPA method |
| 52 | Annex C (normative) STITEL method Table C.1 – Modulation frequencies for the STITEL method |
| 53 | Annex D (informative) RASTI method (obsolete) Table D.1 – Modulation frequencies for the RASTI method |
| 54 | Figure D.1 – Illustration of a practical RASTI test signal |
| 55 | Annex E (informative) Qualification of the STI and relationships with other speech intelligibility measures Figure E.1 – Relationships between some speech intelligibility measures |
| 56 | Figure E.2 – Relationship between STI, speech intelligibility scores and listening difficulty ratings [34], [35] Table E.1 – Categories for listening difficulty |
| 57 | Annex F (informative) Nominal qualification bands for STI Figure F.1 – STI qualification bands |
| 58 | Annex G (informative) Examples of STI qualification bands and typical applications Table G.1 – Examples between STI qualification bands and typical applications |
| 59 | Annex H (informative) Non-native listeners Table H.1 – Adjusted intelligibility qualification tables for non-native listeners |
| 60 | Annex I (informative) Effect of age-related hearing loss and hearing impairment on speech intelligibility Table I.1 – Adjusted intelligibility qualification tables for normal listeners and people over 60 years old with hearing loss |
| 61 | Annex J (normative) Calibration of STI test signal level |
| 63 | Annex K (informative) Example test report sheet for STI measurements |
| 65 | Annex L (normative) Prediction of STI using statistical methods |
| 67 | Annex M (informative) Adjustments to measured STI and STIPA results for simulation of occupancy noise and different speech levels Table M.1 – Example calculation |
| 71 | Annex N (informative) Other methods of determining speech intelligibility |
| 73 | Bibliography |
