1、 IEC 60118-4 Edition 3.0 2014-12 INTERNATIONAL STANDARD NORME INTERNATIONALE Electroacoustics Hearing aids Part 4: Induction-loop systems for hearing aid purposes System performance requirements lectroacoustique Appareils de correction auditive Partie 4: Systmes de boucles dinduction utilises des fi
2、ns de correction auditive Exigences de performances systme IEC 60118-4:2014-12(en-fr) colour inside THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2014 IEC, Geneva, Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form o
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20、ectroacoustics Hearing aids Part 4: Induction-loop systems for hearing aid purposes System performance requirements lectroacoustique Appareils de correction auditive Partie 4: Systmes de boucles dinduction utilises des fins de correction auditive Exigences de performances systme INTERNATIONAL ELECTR
21、OTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE XA ICS 17.140.50 PRICE CODE CODE PRIX ISBN 978-2-8322-1984-3 Registered trademark of the International Electrotechnical Commission Marque dpose de la Commission Electrotechnique Internationale Warning! Make sure that you obtained this
22、publication from an authorized distributor. Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agr. colour inside 2 IEC 60118-4:2014 IEC 2014 CONTENTS FOREWORD . 6 INTRODUCTION . 8 1 Scope 9 2 Normative references 9 3 Terms and definitions 9 4 General . 10 4.
23、1 Procedure for setting 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. .
24、11 5 Using components 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 P
25、eak programme meter (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
26、of the installation 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 measur
27、ement with a simulated 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
28、. 18 8.3.1 Characteristic to be specified . 18 IEC 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 M
29、ethod 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 a
30、nd 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
31、10.2.2 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 Ampl
32、ifier 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 Spec
33、ific 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
34、.3.1 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 4 IEC 60118-4:2014 IEC 2014 Annex C (informative) Provision of information. 33 C.1 General . 33 C.2 Information to be p
35、rovided 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 and practice of au
36、dio-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 Cables . 44 E.5 Care o
37、f 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 strength 49 H.1 Overvie
38、w. 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 operations in this stan
39、dard . 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: inductive coupling 33
40、 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 vertical component
41、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 rectangular loop 41
42、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 IEC 60118-4:2014 IEC 2014 5 Figure F.2 Magnetic field pattern of a 10 m by 14 m loop, 1,2 m above its plane, showing the effe
43、ct 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 Figure H.2 Square and rectangular l
44、oops . 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 6 IEC 60118-4:2014 IEC 2014 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ ELECTROACOU
45、STICS HEARING AIDS Part 4: Induction-loop systems for hearing aid purposes System performance requirements FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). Th
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