1、BSI Standards PublicationElectroacoustics Hearing aidsPart 4: Induction-loop systems for hearing aid purposes System performance requirementsBS EN 60118-4:2015National forewordThis British Standard is the UK implementation of EN 60118-4:2015. It is identical to IEC 60118-4:2014. It supersedes BS EN
2、60118-4:2006 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee EPL/29, Electroacoustics.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisi
3、ons ofa contract. Users are responsible for its correct application. The British Standards Institution 2014Published by BSI Standards Limited 2014ISBN 978 0 580 79122 2ICS 17.140.50Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published und
4、er the authority of theStandards Policy and Strategy Committee on 28 February 2015.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS EN 60118-4:2015EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 60118-4 February 2015 ICS 17.140.50 Supersedes EN 60118-4:2006 Engli
5、sh Version Electroacoustics - Hearing aids - Part 4: Induction-loop systems for hearing aid purposes - System performance requirements (IEC 60118-4:2014) lectroacoustique - Appareils de correction auditive - Partie 4: Systmes de boucles dinduction utilises des fins de correction auditive - Exigences
6、 de performances systme (IEC 60118-4:2014) Akustik - Hrgerte - Teil 4: Induktionsschleifen fr Hrgerte - Leistungsanforderungen (IEC 60118-4:2014) This European Standard was approved by CENELEC on 2015-01-15. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulat
7、e the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CENELEC member. This European
8、Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CENELEC members
9、 are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway
10、, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung CEN-CENELEC Management Centre: Avenue M
11、arnix 17, B-1000 Brussels 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members. Ref. No. EN 60118-4:2015 E BS EN 60118-4:2015EN 60118-4:2015 - 2 - Foreword The text of document 29/855/FDIS, future edition 3 of IEC 60118-4, prepared by IEC TC 29,
12、 Electroacoustics, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 60118-4:2015. The following dates are fixed: latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2015-10-
13、15 latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2018-01-15 This document supersedes EN 60118-4:2006. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CENELEC and/or CEN shall
14、not be held responsible for identifying any or all such patent rights. Endorsement notice The text of the International Standard IEC 60118-4:2014 was approved by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added f
15、or the standards indicated: IEC 61938 NOTE Harmonised as EN 61938. IEC 61260-1 NOTE Harmonised as EN 61260-1. BS EN 60118-4:2015- 3 - EN 60118-4:2015 Annex ZA (normative) Normative references to international publications with their corresponding European publications The following documents, in who
16、le or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. NOTE 1 When an International Publicati
17、on has been modified by common modifications, indicated by (mod), the relevant EN/HD applies. NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here: www.cenelec.eu. Publication Year Title EN/HD Year IEC 60268-3 2013 Sound system equipme
18、nt - Part 3: Amplifiers EN 60268-3 2013 IEC 60268-10 1991 Sound system equipment - Part 10: Peak programme level meters HD 483.10 S1 1993 IEC 61672-1 2013 Electroacoustics - Sound level meters - Part 1: Specifications EN 61672-1 2013 IEC 62489-1 2010 Electroacoustics - Audio frequency induction loop
19、 systems for assisted hearing - Part 1: Methods of measuring and specifying the performance of system components EN 62489-1 2010 BS EN 60118-4:2015 2 IEC 60118-4:2014 IEC 2014 CONTENTS INTRODUCTION . 8 1 Scope 9 2 Normative references 9 3 Terms and definitions 9 4 General . 10 4.1 Procedure for sett
20、ing up and commissioning an audio-frequency induction loop system 10 4.2 Suitability of the site for the installation of an audio-frequency induction-loop system 10 4.3 Relation of the magnetic field strength level at the telecoil to the sound pressure level at the microphone. . 11 5 Using component
21、s of a sound system in an induction-loop system 11 5.1 General . 11 5.2 Microphones . 11 5.3 Mixer 11 5.4 Power amplifier . 11 6 Meters and test signals 11 6.1 Meters 11 6.1.1 Meters in general . 11 6.1.2 Requirements common to both types . 11 6.1.3 True-r.m.s. meter . 12 6.1.4 Peak programme meter
22、(PPM) . 12 6.2 Test signals in general 12 6.3 Speech signals . 13 6.3.1 Live speech signals . 13 6.3.2 Recorded speech material . 13 6.3.3 Simulated speech material . 13 6.4 Pink noise signal . 13 6.5 Sinusoidal signal . 13 6.6 Combi signal . 14 7 Magnetic background noise level of the installation
23、site . 14 7.1 Method of measurement . 14 7.2 Recommended maximum magnetic noise levels 15 8 Characteristics to be specified, methods of measurement and requirements 15 8.1 General . 15 8.2 Magnetic field strength 16 8.2.1 Characteristic to be specified . 16 8.2.2 Method of measurement with a simulat
24、ed speech signal 16 8.2.3 Method of measurement with pink noise 17 8.2.4 Method of measurement with a sinusoidal signal . 17 8.2.5 Method of measurement with a combi signal 17 8.2.6 Method of measurement Other 17 8.2.7 Requirements 17 8.3 Frequency response of the magnetic field . 18 8.3.1 Character
25、istic to be specified . 18 BS EN 60118-4:2015IEC 60118-4:2014 IEC 2014 3 8.3.2 Method of measurement with a simulated speech signal 18 8.3.3 Method of measurement with pink noise 18 8.3.4 Method of measurement with a sinusoidal signal . 18 8.3.5 Method of measurement with combi signal . 19 8.3.6 Met
26、hod of measurement Other 19 8.3.7 Requirements 19 8.4 Useful magnetic field volume 19 8.4.1 Characteristic to be specified . 19 8.4.2 Methods of measurement 19 8.4.3 Requirements 19 9 Small-volume systems . 19 9.1 Inapplicability of the useful magnetic field volume concept 19 9.2 Disabled refuge and
27、 similar call-points 20 9.3 Requirements for disabled refuge and similar call-points . 22 9.4 Counter systems . 22 9.5 Requirements for counter systems 24 10 Setting up (commissioning) the system 24 10.1 Procedure . 24 10.2 Magnetic noise level due to the system . 24 10.2.1 Explanation of term 24 10
28、.2.2 Method of measurement with a speech signal 24 10.2.3 Method of measurement with pink noise 25 10.2.4 Method of measurement with a sinusoidal signal . 25 10.2.5 Method of measurement with a combi signal 25 10.2.6 Method of measurement Other (no input signal) 25 10.2.7 Requirements 25 10.3 Amplif
29、ier overload at 1,6 kHz 25 10.3.1 Explanation of term 25 10.3.2 Methods of test 25 10.4 Requirements . 25 Annex A (informative) Systems for small useful magnetic field volumes . 27 A.1 Overview. 27 A.2 Body-worn audio systems . 27 A.3 Small volume, defined seating, mainly in households 27 A.4 Specif
30、ic locations such as help and information points, ticket and bank counters, etc. 27 Annex B (informative) Measuring equipment 30 B.1 Overview. 30 B.2 Signal sources 30 B.2.1 Real speech 30 B.2.2 Simulated speech 30 B.2.3 Pink noise 30 B.2.4 Sine wave 30 B.3 Magnetic field strength level meter 31 B.3
31、.1 General recommendations . 31 B.3.2 Peak-programme meter (PPM) type . 31 B.3.3 True r.m.s. meter type . 31 B.4 Field strength level meter calibrator 32 B.5 Spectrum analyzer 32 BS EN 60118-4:2015 4 IEC 60118-4:2014 IEC 2014 Annex C (informative) Provision of information. 33 C.1 General . 33 C.2 In
32、formation to be provided to the hearing aid user 33 C.3 Information to be provided to system installers and by them to users 34 C.4 Information to be provided by the manufacturer of the amplifying equipment . 34 Annex D (informative) Measuring speech signals . 35 Annex E (informative) Basic theory a
33、nd practice of audio-frequency induction-loop systems 36 E.1 Properties of the loop and its magnetic field 36 E.2 Directional response of the telecoil of a hearing aid 37 E.3 Supplying the loop current 42 E.4 Signal sources and cables 43 E.4.1 Microphones 43 E.4.2 Other signal sources 44 E.4.3 Cable
34、s . 44 E.5 Care of the system 44 E.6 Magnetic units 44 Annex F (informative) Effects of metal in the building structure on the magnetic field . 45 Annex G (informative) Calibration of field-strength meters . 47 Annex H (informative) Effect of the aspect ratio of the loop on the magnetic field streng
35、th 49 H.1 Overview. 49 H.2 Effect of aspect ratio on field patterns . 49 Annex I (informative) Overspill of magnetic field from an induction-loop system . 51 I.1 General . 51 I.2 Examples of overspill issues . 51 I.3 Addressing overspill issues . 51 Bibliography 53 Figure 1 Flow chart for the operat
36、ions in this standard . 10 Figure 2 Measurement points for disabled refuge and similar call-points 21 Figure 3 Measurement points for a counter system 23 Figure A.1 Field pattern of a vertical loop . 28 Figure A.2 Contour plot of field strength of vertical loop . 29 Figure C.1 Graphical symbol: indu
37、ctive coupling 33 Figure E.1 Perspective view of a loop, showing the magnetic field vector paths . 37 Figure E.2 Strengths of the components of the magnetic field due to current in a horizontal rectangular loop at points in a plane above or below the loop plane 38 Figure E.3 Field patterns of the ve
38、rtical component of the magnetic field of a horizontal loop 39 Figure E.4 Field patterns of the vertical component of the magnetic field of a vertical loop 0,75 m square . 40 Figure E.5 Perspective view of the variation of the vertical field strength level at an optimum height above a horizontal rec
39、tangular loop 41 Figure E.6 Directional response of the magnetic pick-up coil (telecoil) of a hearing aid 42 Figure F.1 Magnetic field pattern of a 10 m by 14 m loop, 1,2 m above its plane 45 BS EN 60118-4:2015IEC 60118-4:2014 IEC 2014 5 Figure F.2 Magnetic field pattern of a 10 m by 14 m loop, 1,2
40、m above its plane, showing the effect of metal (iron) in the floor 46 Figure G.1 Triple Helmholtz coil for calibration of meters . 47 Figure H.1 Variation of the current required to produce a specified magnetic field strength at a specific point with the dimensions and aspect ratio of the loop . 49
41、Figure H.2 Square and rectangular loops . 50 Table 1 Application of signals 12 Table 2 Specification of the combi signal . 14 Table 3 Magnetic field strengths typically produced by different test signals, with an amplifier having peak-detecting AGC 17 BS EN 60118-4:2015 8 IEC 60118-4:2014 IEC 2014 I
42、NTRODUCTION Audio-frequency induction-loop systems are widely used to provide a means for hearing aid users, whose hearing aids are fitted with induction pick-up coils, generally known as telecoils, to minimise the problems of listening when at a distance from a source of sound, shielded from the pe
43、rson speaking by a protective window, and/or in a background noise. Background noise and distance are two of the main causes of hearing aid users being unable to hear satisfactorily in other than face-to-face quiet conditions. Induction-loop systems have been widely installed in churches, theatres a
44、nd cinemas, for the benefit of hearing-impaired people. The use of induction-loop systems has been extended to many transient communication situations such as ticket offices, bank counters, drive-in/drive-through service locations, lifts/elevators etc. The widespread provision of telephone handsets
45、that provide inductive coupling to hearing aids is another significant application, where ITU-T Recommendation P370 11applies. Transmission of an audio-frequency signal via an induction-loop system can often establish an acceptable signal-to-noise ratio in conditions where a purely acoustical transm
46、ission would be significantly degraded by reverberation and background noise. One form of audio frequency induction-loop system comprises a cable installed in the form of a loop usually around the perimeter of a room or area in which a group of hearing impaired persons wish to listen. The cable is c
47、onnected via an amplifier to a microphone system or other source of audio signal, such as a radio receiver, CD player etc. The amplifier produces an audio-frequency electric current in the induction loop cable, causing a magnetic field to be produced inside the loop. The design and implementation of
48、 the induction loop is determined by the construction of the building in which it is installed, particularly by the presence of large amounts of iron, steel or aluminium in the structure. In addition the layout and position of electrical cables and equipment may generate high levels of background au
49、dio frequency magnetic fields that may interfere with the reception of the loop signal. Another form of induction-loop system employs a small loop, intended for communication with a hearing-aid user in its immediate vicinity. Examples are: neck loops, ticket-counter systems, self-contained portable systems and chairs incorporating induction loops. (See Annex A) The pick-up device for an audio-frequency induction-loop system is usually a personal hearing aid,
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