prEN IEC 60268-16:2019
(Main)IEC 60268-16:2020 defines the STI model, test signals, measurement and prediction methods. The objective of this document is to provide a comprehensive manual for all types of users of the STI model in the fields of audio, communications and acoustics. This document does not provide STI criteria for certification of transmission channels (e.g. criteria for a voice-alarm system), but some typical application values are provided in Annex G. Every measurement method has limitations, and the reader is referred to clauses relating to limitations such as speech privacy, echo and systems using digital voice compression (vocoders). This document does not cover the case of fluctuating noise on the STI, although some general comments on dealing with this complex issue are provided in 7.13 and 8.9.3. IEC 60268-16:2020 cancels and replaces the fourth edition published in 2011. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) the spectrum of the male speech test signal has been changed, with significant reductions in the 125 Hz and 250 Hz bands being implemented; b) some corrections to formulae have been made; c) additional information has been included on prediction and measurement procedures; d) spectrum and weighting factors for female speech have been removed; e) verification information for STI measurement devices added; f) the relationships between STI and number of other speech intelligibility measures have been updated in Annex E; g) greater information is given in Annex M about adjustments to the measured STI results to simulate effects of alternative ambient noise and speech levels.
Elektroakustische Geräte - Teil 16: Objektive Bewertung der Sprachverständlichkeit durch den Sprachübertragungsindex
Equipements pour systèmes électroacoustiques - Partie 16: Évaluation objective de l'intelligibilité de la parole au moyen de l'indice de transmission de la parole
L'IEC 60268-16:2020 définit le modèle, les signaux d'essai, la mesure et les méthodes de prévision STI. L'objectif du présent document est de mettre un manuel complet à la disposition de tous les types d'utilisateurs du modèle STI dans les domaines de l'audio, des communications et de l'acoustique. Le présent document ne donne pas de critères STI destinés à la certification des canaux de transmission (par exemple, critères pour un système d'alarme vocale), mais certaines valeurs d'application courante sont fournies dans l'Annexe G. Chaque méthode de mesure présente ses limites, et le lecteur est prié de se référer aux articles correspondants, par exemple concernant la confidentialité des conversations, l'écho et les systèmes qui utilisent la compression vocale numérique (vocodeurs). Le présent document ne couvre pas les cas du bruit fluctuant sur le STI, bien que certains commentaires généraux qui traitent de cette question complexe soient fournis en 7.13 et 8.9.3. L'IEC 60268-16:2020 annule et remplace la quatrième édition parue en 2011. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: a) le spectre du signal d'essai de la parole masculine a été modifié pour appliquer des réductions significatives au niveau des bandes de 125 Hz et 250 Hz; b) certaines formules ont été corrigées; c) des informations supplémentaires relatives aux modes opératoires de prédiction et de mesure ont été incluses; d) le spectre et les facteurs de pondération pour la parole féminine ont été supprimés; e) des informations de vérification pour les dispositifs de mesure STI ont été ajoutées; f) les relations entre le STI et plusieurs autres mesures de l'intelligibilité de la parole ont été mises à jour en Annexe E; g) des informations supplémentaires sont données en Annexe M concernant les ajustements des résultats STI mesurés afin de simuler les effets d'autres niveaux de bruit ambiant et de parole.
Oprema za zvokovne sisteme - 16. del: Objektivno ocenjevanje govorne razumljivosti z uporabo indeksa prenosa govora
General Information
RELATIONS
Standards Content (sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Oprema za zvokovne sisteme - 16. del: Objektivno ocenjevanje govorne razumljivosti z uporabo indeksa prenosa govoraElektroakustische Geräte - Teil 16: Objektive Bewertung der Sprachverständlichkeit durch den SprachübertragungsindexEquipements pour systèmes électroacoustiques - Partie 16: Evaluation objective de l'intelligibilité de la parole au moyen de l'indice de transmission de la paroleSound system equipment - Part 16: Objective rating of speech intelligibility by speech transmission index33.160.30Avdio sistemiAudio systemsICS:Ta slovenski standard je istoveten z:prEN IEC 60268-16:2019oSIST prEN IEC 60268-16:2019en,fr,de01-maj-2019oSIST prEN IEC 60268-16:2019SLOVENSKI
STANDARDoSIST prEN IEC 60268-16:2019
100/3202/CDV COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER: IEC 60268-16 ED5
DATE OF CIRCULATION: CLOSING DATE FOR VOTING: 2019-03-08 2019-05-31
SUPERSEDES DOCUMENTS: 100/3012/CD,100/3171/CC
IEC TA 20 : ANALOGUE AND DIGITAL AUDIO SECRETARIAT: SECRETARY: Japan Mr Gen Ichimura OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
Other TC/SCs are requested to indicate their interest, if any, in this CDV to the secretary. FUNCTIONS CONCERNED:
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TITLE: Sound system equipment - Part 16: Objective rating of speech intelligibility by speech transmission index
PROPOSED STABILITY DATE: 2022NOTE FROM TC/SC OFFICERS:
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oSIST prEN IEC 60268-16:2019oSIST prEN IEC 60268-16:2019
– 2 – 60268-16/Ed.5 IEC(3)
CONTENTS 1
2 FOREWORD ........................................................................................................................... 7 3 INTRODUCTION ..................................................................................................................... 9 4 1 Scope ............................................................................................................................ 12 5 2 Normative references .................................................................................................... 12 6 3 Terms and definitions .................................................................................................... 12 7 4 Description of the STI model ......................................................................................... 17 8 4.1 Overview .............................................................................................................. 17 9 4.1.1 Applicability of the STI model ........................................................................ 18 10 4.2 Theoretical details ................................................................................................ 18 11 4.2.1 Envelope function and envelope spectrum ..................................................... 18 12 4.2.2 Reduction of modulation ................................................................................ 19 13 4.2.3 Role of the octave-band noise carriers ........................................................... 19 14 4.2.4 Theoretical overview ...................................................................................... 20 15 4.3 Measurement of STI.............................................................................................. 22 16 4.3.1 Direct and Indirect Methods ........................................................................... 22 17 4.3.2 FULL STI ....................................................................................................... 22 18 4.3.3 STIPA ............................................................................................................ 23 19 4.3.4 Choice of method .......................................................................................... 23 20 5 Direct method of measuring STI – User guidance .......................................................... 25 21 5.1 Overview .............................................................................................................. 25 22 5.2 STIPA ................................................................................................................... 25 23 5.3 Application ............................................................................................................ 26 24 5.4 Limitations ............................................................................................................ 26 25 6 Indirect method of measuring STI (impulse response) – User guidance ......................... 26 26 6.1 Overview .............................................................................................................. 26 27 6.2 Application ............................................................................................................ 27 28 6.3 Limitations (non-linear distortion) .......................................................................... 28 29 7 Limitations of the STI model .......................................................................................... 28 30 7.1 General ................................................................................................................. 28 31 7.2 Frequency shifts ................................................................................................... 29 32 7.3 Centre clipping ...................................................................................................... 29 33 7.4 Dropouts ............................................................................................................... 30 34 7.5 Jitter ..................................................................................................................... 30 35 7.6 Digital voice compression systems ........................................................................ 30 36 7.7 Overestimation of STI under low background noise conditions .............................. 30 37 7.8 Frequency response ............................................................................................. 30 38 7.9 Echoes ................................................................................................................. 31 39 7.10 Fast amplitude compression and expansion .......................................................... 33 40 7.11 Non-linear distortion ............................................................................................. 34 41 7.12 Hearing impaired listeners .................................................................................... 34 42 7.13 Impulsive and fluctuating noise ............................................................................. 34 43 7.14 Conclusion ............................................................................................................ 35 44 8 Measurement procedures, post-processing of data and applications .............................. 35 45 8.1 General ................................................................................................................. 35 46 oSIST prEN IEC 60268-16:2019
60268-16/Ed.5 IEC(3) – 3 –8.2 Acoustical input .................................................................................................... 35 47 8.3 Acoustical output .................................................................................................. 37 48 8.4 Electrical input ...................................................................................................... 37 49 8.5 Electrical output .................................................................................................... 37 50 8.6 Examples of input/output combinations ................................................................. 37 51 8.6.1 Acoustical input – Acoustical output ............................................................... 37 52 8.6.2 Electrical input – Electrical output (e.g. assessment of wired and 53 wireless) communication systems) ................................................................. 38 54 8.6.3 Acoustical input – Electrical output (e.g. assessment of microphones) ........... 38 55 8.6.4 Electrical input – Acoustical output (e.g. assessment of PA systems) ............ 38 56 8.7 Spatial averaging of STI measurements ................................................................ 38 57 8.8 Post-processing of measured MTF data ................................................................ 39 58 8.9 Issues concerning noise........................................................................................ 40 59 8.9.1 General ......................................................................................................... 40 60 8.9.2 Measurement of background noise ................................................................ 40 61 8.9.3 Fluctuating noise ........................................................................................... 40 62 8.10 Analysis and interpretation of the results .............................................................. 41 63 8.11 Binaural STI measurements .................................................................................. 41 64 9 Use of STI as a design prediction tool ........................................................................... 42 65 9.1 Overview .............................................................................................................. 42 66 9.2 Statistical predictions ............................................................................................ 42 67 9.3 Prediction from simulated impulse response ......................................................... 42 68 Annex A (informative) The basis of the STI concept .............................................................. 44 69 A.1 Introduction to this Annex ..................................................................................... 44 70 A.1.1 Purpose ......................................................................................................... 44 71 A.1.2 Modulation transfer function (MTF) ................................................................ 44 72 A.1.3 STI model ...................................................................................................... 45 73 A.1.4 STI modulation frequencies ........................................................................... 46 74 A.2 Calculation of the STI ........................................................................................... 46 75 A.2.1 General Equation for STI ............................................................................... 46 76 A.2.2 Gender-specific octave band weighting and redundancy factors .................... 47 77 A.2.3 Adjustment of the MTF for ambient noise ....................................................... 48 78 A.2.4 Adjustment of the MTF for auditory masking and threshold effects ................. 48 79 A.3 Calculation of the modulation transfer ratio values ................................................ 49 80 A.3.1 Direct method: Analysis of the STI test signal ................................................ 49 81 A.3.2 Indirect method: Determination of the modulation transfer function (MTF)82
50 83 A.4 Auditory effects on the STI ..................................................................
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