This part of IEC 60268 specifies objective methods for rating the transmission quality of speech with respect to intelligibility.<\/p>\n
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.<\/p>\n
This standard does not provide STI criteria for certification of transmission channels (e.g . criteria for a voice-alarm system).<\/p>\n
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.<\/p>\n
\nNOTE 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.<\/p>\n<\/blockquote>\n
The following information is included:<\/p>\n
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measurement techniques ;<\/p>\n<\/li>\n
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prediction techniques.<\/p>\n<\/li>\n<\/ul>\n
PDF Catalog<\/h4>\n
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\n PDF Pages<\/th>\n PDF Title<\/th>\n<\/tr>\n \n 6<\/td>\n CONTENTS <\/td>\n<\/tr>\n \n 9<\/td>\n FOREWORD <\/td>\n<\/tr>\n \n 11<\/td>\n INTRODUCTION <\/td>\n<\/tr>\n \n 13<\/td>\n 1 Scope
2 Normative references
3 Terms and definitions <\/td>\n<\/tr>\n\n 19<\/td>\n 4 Description of the STI method
4.1 General <\/td>\n<\/tr>\n\n 20<\/td>\n 4.2 Background of the STI method
Figures
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Figure 1 \u2013 Concept of the reduction in modulation due to a transmission channel <\/td>\n<\/tr>\n\n 21<\/td>\n Figure 2 \u2013 Modulation transfer function \u2013 Input\/output comparison <\/td>\n<\/tr>\n \n 23<\/td>\n 4.3 Applicability of STI test methods
Tables
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Table 1 \u2013 Comparison of STI test methods for different types of distortion <\/td>\n<\/tr>\n\n 24<\/td>\n 4.4 Use of direct and indirect methods
Table 2 \u2013 Applicability of test <\/td>\n<\/tr>\n\n 25<\/td>\n 4.5 Limitations of the STI method
Table 3 \u2013 Choice of method <\/td>\n<\/tr>\n\n 28<\/td>\n 4.6 Conclusion
5 Direct method of measuring STI
5.1 Overview <\/td>\n<\/tr>\n\n 29<\/td>\n 5.2 STIPA <\/td>\n<\/tr>\n \n 30<\/td>\n 5.3 Application
5.4 Limitations
6 Indirect method of measuring STI using the impulse response
6.1 Overview <\/td>\n<\/tr>\n\n 31<\/td>\n 6.2 Application <\/td>\n<\/tr>\n \n 32<\/td>\n 6.3 Limitations (non-linear distortion)
7 Measurement procedures, post-processing of data and applications
7.1 General
7.2 Acoustical input <\/td>\n<\/tr>\n\n 34<\/td>\n 7.3 Acoustical output
7.4 Electrical input
7.5 Electrical output
7.6 Examples of input\/output combinations <\/td>\n<\/tr>\n\n 35<\/td>\n 7.7 Post-processing of measured MTF data
7.8 Issues concerning noise <\/td>\n<\/tr>\n\n 36<\/td>\n 7.9 Analysis and interpretation of the results <\/td>\n<\/tr>\n \n 37<\/td>\n 7.10 Binaural STI measurements
8 Use of STI as a design prediction tool
8.1 Overview
8.2 Statistical predictions <\/td>\n<\/tr>\n\n 38<\/td>\n 8.3 Prediction from simulated impulse response <\/td>\n<\/tr>\n \n 39<\/td>\n Annex A (normative)
\nSpeech transmission index (STI) and revised STI methods
Figure A.1 \u2013 Envelope function (panel A) of a 10\u00a0s speech signal for the 250\u00a0Hz octave band and corresponding envelope spectrum (panel B) <\/td>\n<\/tr>\n\n 40<\/td>\n Figure A.2 \u2013 Theoretical expression of the MTF <\/td>\n<\/tr>\n \n 42<\/td>\n Figure A.3 \u2013 Measurement system and frequencies for the STI method <\/td>\n<\/tr>\n \n 43<\/td>\n Figure A.4 \u2013 Auditory masking of octave band (k\u00a0\u2013\u00a01) on octave band (k) <\/td>\n<\/tr>\n \n 44<\/td>\n Table A.1 \u2013 Auditory masking as a function of the octave band level <\/td>\n<\/tr>\n \n 45<\/td>\n Table A.2 \u2013 Absolute speech reception threshold level in octave bands
Table A.3 \u2013 MTI octave band weighting factors <\/td>\n<\/tr>\n\n 46<\/td>\n Table A.4 \u2013 Octave band levels (dB) relative to the A-weighted speech level <\/td>\n<\/tr>\n \n 51<\/td>\n Annex B (normative)
\nSTIPA method
Table B.1 \u2013 Modulation frequencies for the STIPA method <\/td>\n<\/tr>\n\n 52<\/td>\n Annex C (normative)
\nSTITEL method
Table C.1 \u2013 Modulation frequencies for the STITEL method <\/td>\n<\/tr>\n\n 53<\/td>\n Annex D (informative)
\nRASTI method (obsolete)
Table D.1 \u2013 Modulation frequencies for the RASTI method <\/td>\n<\/tr>\n\n 54<\/td>\n Figure D.1 \u2013 Illustration of a practical RASTI test signal <\/td>\n<\/tr>\n \n 55<\/td>\n Annex E (informative)
\nQualification of the STI and relationships with other speech intelligibility measures
Figure E.1 \u2013 Relationships between some speech intelligibility measures <\/td>\n<\/tr>\n\n 56<\/td>\n Figure E.2\u00a0\u2013\u00a0Relationship between STI, speech intelligibility scores and listening difficulty ratings [34], [35]
Table E.1 \u2013 Categories for listening difficulty <\/td>\n<\/tr>\n\n 57<\/td>\n Annex F (informative)
\nNominal qualification bands for STI
Figure F.1 \u2013 STI qualification bands <\/td>\n<\/tr>\n\n 58<\/td>\n Annex G (informative)
\nExamples of STI qualification bands and typical applications
Table G.1 \u2013 Examples between STI qualification bands and typical applications <\/td>\n<\/tr>\n\n 59<\/td>\n Annex H (informative)
\nNon-native listeners
Table H.1 \u2013 Adjusted intelligibility qualification tables for non-native listeners <\/td>\n<\/tr>\n\n 60<\/td>\n Annex I (informative)
\nEffect of age-related hearing loss and hearing impairment on speech intelligibility
Table I.1 \u2013 Adjusted intelligibility qualification tables for normal listeners and people over 60 years old with hearing loss <\/td>\n<\/tr>\n\n 61<\/td>\n Annex J (normative)
\nCalibration of STI test signal level <\/td>\n<\/tr>\n\n 63<\/td>\n Annex K (informative)
\nExample test report sheet for STI measurements <\/td>\n<\/tr>\n\n 65<\/td>\n Annex L (normative)
\nPrediction of STI using statistical methods <\/td>\n<\/tr>\n\n 67<\/td>\n Annex M (informative) Adjustments to measured STI and STIPA results for simulation
\nof occupancy noise and different speech levels
Table M.1\u00a0\u2013\u00a0Example calculation <\/td>\n<\/tr>\n\n 71<\/td>\n Annex N (informative)
\nOther methods of determining speech intelligibility <\/td>\n<\/tr>\n\n 73<\/td>\n Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Sound system equipment – Objective rating of speech intelligibility by speech transmission index<\/b><\/p>\n
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\n Published By<\/td>\n Publication Date<\/td>\n Number of Pages<\/td>\n<\/tr>\n \n BSI<\/b><\/a><\/td>\n 2011<\/td>\n 78<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":228701,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[637,2641],"product_tag":[],"class_list":{"0":"post-228699","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-33-160-01","7":"product_cat-bsi","9":"first","10":"instock","11":"sold-individually","12":"shipping-taxable","13":"purchasable","14":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/228699","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/types\/product"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media\/228701"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=228699"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=228699"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=228699"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}