1、DEUTSCHE NORM February 2004 DIN EN IS0 9921 DIN ICs 13.040 Supersedes DIN 3341 O, December 1981 edition. Ergonomics (IS0 9921 : 1995) English version of DIN EN IS0 9921 Assessment of speech communication Ergonomie - Beurteilung der Sprachkommunikation (IS0 9921 : 2003) European Standard EN IS0 9921
2、: 2003 has the status of a DIN Standard. A comma is used as the decimal marker. National foreword This standard has been published in accordance with a decision taken by CEN/TC 122 to adopt, without alteration, International Standard IS0 9921 as a European Standard. The responsible German body invol
3、ved in its preparation was the Normenausschuss Ergonomie (Ergonom- ics Standards Committee), Technical Committee Optische und akustische Verstndigung. Amendments DIN 33410, December 1981 edition, has been superseded by the specifications of EN IS0 9921, which is identical to IS0 9921. Previous editi
4、on DIN 3341 O: 1981 -1 2. Document comprises 31 pages. 1111 II II II III 1111 1111 I O No part of this standard may be reproduced without the prior permission of DIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GrnbH, 10772 Berlin, Germany, has the exclusive right of sale for German Sta
5、ndards (DIN-Normen). English price group 15 www.din.de www. beuth.de 05.04 95531 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN IS0 9921 October 2003 ICs 13.180 English version Ergonomics (IS0 9921 : 1995) Assessment of speech commun cat ion Ergonomie - Evaluation de la com- munication parle (
6、IS0 9921 : 2003) Ergonomie - Beurteilung der Sprach- kommunikation (IS0 9921 : 2003) This European Standard was approved by CEN on 2003-1 0-01. CEN members are bound to comply with the CENKENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a na
7、tional standard without any alteration. Up-to-date lists and bibliographical references concerning such national stand- ards may be obtained on application to the Management Centre or to any CEN member. The European Standards exist in three official versions (English, French, German). A version in a
8、ny other language made by translation under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, the Czech Republic, Denmark, Finland, France, Ge
9、rmany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta, the Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland, and the United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Management Centre: rue de Stas
10、sart 36, B-1050 Brussels O 2003. CEN - All rights of exploitation in any form and by any means reserved worldwide for CEN national members. Ref. No. EN IS0 9921 : 2003 E Page 2 EN IS0 9921 : 2003 Foreword International Standard IS0 9921 : 2003 Ergonomics . Assessment of speech communication. which w
11、as prepared by ISO/TC 159 Ergonomics of the International Organization for Standardization. has been adopted by Technical Committee CEN/TC 122 Ergonomics. the Secretariat of which is held by DIN. as a European Standard . This European Standard shall be given the status of a national standard. either
12、 by publication of an identical text or by endorsement. and conflicting national standards withdrawn. by April 2004 at the latest . In accordance with the CENKENELEC Internal Regulations. the national standards organizations of the follow- ing countries are bound to implement this European Standard:
13、 Austria. Belgium. the Czech Republic. Denmark. Finland. France. Germany. Greece. Hungary. Iceland. Ireland. Italy. Luxembourg. Malta. the Netherlands. Norway. Portugal. Slovakia. Spain. Sweden. Switzerland. and the United Kingdom . Endorsement notice The text of the International Standard IS0 9921
14、: 2003 was approved by CEN as a European Standard without any modification . Contents Page Foreword . 2 Introduction 3 1 2 3 4 4.1 4.2 4.3 4.4 5 5.1 5.2 5.3 5.4 5.5 5.6 6 6.1 6.2 6.3 Scope Normative references . Terms and definitions . Descriptions of speech communications . General . Transmission c
15、hannel Listener Performance of speech communications . General . Alert and warning situations Person-to-person communications . Public address in public areas Personal communication systems Summary of recommended minimum performance Assessment and prediction . General . Subjective assessment methods
16、 Objective assessment and prediction methods Speaker 4 4 4 6 6 6 6 6 6 6 7 7 7 8 8 8 8 8 9 Annex A (normative) Speaker and listener characteristics . 10 Annex B (informative) Subjective speech-intelligibility tests 12 Annex C (informative) Speech transmission index. STI . 15 Annex D (informative) Ov
17、erview of the means of communication and related parameters . 17 Annex E (normative) Speech interference level. SIL 21 Annex F (informative) Intelligibility ratings for speech communications . 22 Annex G (normative) Definition of symbols 24 Annex H (informative) Examples of applications of predictiv
18、e intelligibility methods . 25 Bibliography . 30 Page 3 EN IS0 9921 : 2003 Introduction The aim of standardization in the field of the ergonomic assessment of speech-communication is to recommend the levels of speech-communication quality required for conveying comprehensive messages in different ap
19、plications. The quality of speech communication is assessed for the following cases: - warning of hazard; - warning of danger; - information messages for work places, public areas, meeting rooms, and auditoria. For some applications, direct communication between humans is considered while, in others
20、, the use of electro-acoustic systems (e.g. PA systems) or personal communication equipment (e.g. telephone, intercom) will be the most convenient means of informing and instructing or exchanging information. The use of auditory warning symbols other than speech is not included in this International
21、 Standard but is covered by IS0 7731. Acoustical danger and warning signals are in general omni-directional and therefore may be universal in many situations. Auditory warnings are of great benefit in situations where smoke, darkness or other obstructions interfere with visual warnings. It is essent
22、ial that, in the case of verbal messages, a sufficient level of intelligibility is achieved, in the coverage area. If this cannot be achieved, non-voice warning signals (see IS0 7731, IEC 60849 and 4 in the Bibliography) or visual warning signals (see IS0 11429) may be preferable. If acoustical sign
23、als are too loud, hearing damage or environmental problems may occur (e.g. noise nuisance to dwellings near railway platforms, road traffic, airports, etc.). Good design can minimize these negative aspects. In addition, prediction methods with sufficient accuracy are useful for consultants, supplier
24、s and end- users and may thus reduce costs of necessary adjustments after installation of a system. The communications might be directly between humans, through public address or intercom systems or by pre-recorded messages. In general, text-to-speech systems are not recommended because of the low i
25、ntelligibility of these systems. It is recognized that, in a general-purpose document, simple to apply and easily available tools for prediction and assessment should be described, as well as more sophisticated advanced technological methodologies. Page 4 EN IS0 9921 : 2003 1 Scope This Internationa
26、l Standard specifies the requirements for the performance of speech communication for verbal alert and danger signals, information messages, and speech communication in general. Methods to predict and to assess the subjective and objective performance in practical applications are described and exam
27、ples are given. In order to obtain optimal performance in a specific application, three stages can be considered: a) specification of the application and definition of the corresponding performance criteria; b) design of a communication system and prediction of the performance; c) assessment of the
28、performance for in situ conditions. The use of auditory warning signals other than speech is not included in this International Standard but is covered by IS0 7731. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references,
29、 only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISOiTR 4870:1991, Acoustics - The construction and calibration of speech intelligibility tests IEC 60268-1 6: 1998, Sound system equipment - Part 16: Objective r
30、ating of speech intelligibility by speech transmission index 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 alarm warning of existing or approaching danger 3.2 danger risk of harm or damage 3.3 effective signal-to-noise ratio measure to expr
31、ess the (combined) effect of various types of distortions on the intelligibility of a speech signal in terms of the effect of a masking noise resulting in a speech signal having the same intelligibility 3.4 emergency imminent risk or serious threat to persons or property Page 5 EN IS0 9921 : 2003 3.
32、5 Lombard effect spontaneous increase of the vocal effort induced by the increase of the ambient noise level at the speakers ear 3.6 non-native speaker person speaking a language which is different from the language that was learned as the primary language during the childhood of the speaker 3.7 spe
33、ech communication conveying or exchanging information using speech, speaking, hearing modalities, and understanding NOTE Speech communication may involve brief texts, sentences, groups of words and/or isolated words. 3.8 speech communicability rating of the ease with which speech communication is pe
34、rformed NOTE Speech communicability includes speech intelligibility, speech quality, vocal effort, and delays. 3.9 speech intelligibility rating of the proportion of speech that is understood NOTE Speech intelligibility is usually quantified as the percentage of a message understood correctly. 3.10
35、speech intelligibility index SI1 objective method for prediction of intelligibility based on the Articulation Index NOTE See I in the Bibliography. 3.1 1 speech interference level SIL difference between A-weighted speech level and the arithmetic average of sound-pressure levels of ambient noise in f
36、our octave bands with central frequencies of 500 Hz, 1 O00 Hz, 2 O00 Hz and 4 O00 Hz 3.12 speech quality rating of sound quality of a speech signal NOTE description. Speech quality characterizes the amount of audible distortion of a speech signal and is usually rated by a 3.1 3 speech transmission i
37、ndex STI objective method for prediction and measurement of speech intelligibility 3.14 vocal effort exertion of the speaker, quantified objectively by the A-weighted speech level at 1 m distance in front of the mouth and qualified subjectively by a description Page 6 EN IS0 9921 : 2003 3.1 5 warnin
38、g important notice concerning any change of status that demands attention or activity 4 Descriptions of speech communications 4.1 General Speech communication requires three sequential components: speaker, transmission channel and listener(c). Based on this concept, three means of communication are
39、identified. a) Direct communication. This is typical for person-to-person communications, where both persons are in the same environment without making use of electro-acoustic means. b) Public address. In general, an electro-acoustic system that is used to address a group of people in one or more en
40、vironments. c) Personal communication systems. These include the use of mobile telephones and handheld transceivers and the use of normal telephones, intercoms and hands-free telephones. 4.2 Speaker Several speaker-related parameters define the contribution of the speaker to the performance of a com
41、munication. These parameters include vocal effort, speaking quality, gender, accents, non-native speech, speaking disorders, and distance from the listener or microphone. Vocal effort is expressed by the equivalent A-weighted sound-pressure level at a distance of 1 m in front of the mouth. The ambie
42、nt noise level at the speakers position (causing the Lombard effect) and the wearing of a hearing protector influence the vocal effort. The relation between these parameters and the effect on the speech quality is described in Annex A. The frequency spectrum of the speech is related to the gender of
43、 the speaker and the vocal effort. This may result, in combination with a specific type of noise, in a gender-related performance see Annex B (B.3) and Annex CI. The effects of strong accents and non-native speakers and listeners reduce the performance of a communication; quantitative data are given
44、 in A.6. 4.3 Transmission channel The transmission path between the speakers mouth and the listeners ear is described by the distribution of the speech signal in a room or by an electro-acoustic system. It affects the deterioration of the speech signal. Important influences are ambient noise, reverb
45、eration, echoes, sound radiation, limitation in the frequency response, and non-linearities. In Annex D, an overview is given of the means of communication and related parameters. 4.4 Listener For the listener, hearing aspects (directional hearing, masking, hearing disorders, reception threshold) an
46、d the use of hearing protection define the deterioration. In Annexes A, C, D and E, these listener-related parameters are considered, except for that of directional hearing, which is not considered in this International Standard. 5 Performance of speech communications 5.1 General A correct recogniti
47、on of each utterance is required for the understanding of spoken messages. In technical terms, this means that an intelligibility score of 100 % is required for sentences. A sentence intelligibility score Page 7 EN IS0 9921 : 2003 of 100% does not imply that each individual word is clearly understoo
48、d and that the listening situation is comfortable and relaxed and there are many situations in which a better performance is required. In alert situations under adverse conditions, it is sufficient to fully understand a short message, even if correct understanding requires some effort from the liste
49、ner. In a meeting room, an auditorium, or at work places where speech communication is a part of the task and where people are normally present for a longer period of time, a more relaxed speaking condition and a good listening condition are required. For the speaker, this is reflected by the low vocal effort required to be understood (see Table A.l). For the listener, the listening effort may be primarily related to the speech intelligibility and speech quality at the listening position (see Table F.l). The range of the classification scales and the number of the interv
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