BS EN IEC 60118-4:2015+A1:2018
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Electroacoustics. Hearing aids – Induction-loop systems for hearing aid purposes. System performance requirements
| Published By | Publication Date | Number of Pages |
| BSI | 2018 | 58 |
This part of IEC 60118 is applicable to audio-frequency induction-loop systems producing an alternating magnetic field at audio frequencies and intended to provide an input signal for hearing aids operating with an induction pick-up coil (telecoil). Throughout this standard, it is assumed that the hearing aids used with it conform to all relevant parts of IEC 60118.
This standard specifies requirements for the field strength in audio-frequency induction loops for hearing aid purposes, which will give adequate signal-to-noise ratio without overloading the hearing aid. The standard also specifies the minimum frequency response requirements for acceptable intelligibility.
Methods for measuring the magnetic field strength are specified, and information is given on appropriate measuring equipment (see Annex B), information that should be provided to the operator and users of the system (see Annex C), and other important considerations.
This standard does not specify requirements for loop driver amplifiers or associated microphone or audio signal sources, which are dealt with in IEC 62489-1, or for the field strength produced by equipment, such as telephone handsets, within the scope of ITU-T P.370.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | National foreword |
| 4 | European foreword Anchor 3 Foreword to amendment A1 |
| 5 | Annex ZA (normative) Normative references to international publications with their corresponding European publications |
| 8 | FOREWORD |
| 10 | INTRODUCTION |
| 11 | 1 Scope 2 Normative references 3 Terms and definitions |
| 12 | 4 General 4.1 Procedure for setting up and commissioning an audio-frequency induction loop system |
| 13 | 4.2 Suitability of the site for the installation of an audio-frequency induction-loop system 4.3 Relation of the magnetic field strength level at the telecoil to the sound pressure level at the microphone. 5 Using components of a sound system in an induction-loop system 5.1 General 5.2 Microphones 5.3 Mixer 5.4 Power amplifier |
| 14 | 6 Meters and test signals 6.1 Meters 6.1.1 Meters in general 6.1.2 Requirements common to both types 6.1.3 True-r.m.s. meter 6.1.4 Peak programme meter (PPM) 6.2 Test signals in general |
| 15 | 6.3 Speech signals 6.3.1 Live speech signals 6.3.2 Recorded speech material 6.3.3 Simulated speech material |
| 16 | 6.4 Pink noise signal 6.5 Sinusoidal signal 6.6 Combi signal |
| 17 | 7 Magnetic background noise level of the installation site 7.1 Method of measurement 7.2 Recommended maximum magnetic noise levels |
| 18 | 8 Characteristics to be specified, methods of measurement and requirements 8.1 General 8.2 Magnetic field strength 8.2.1 Characteristic to be specified |
| 19 | 8.2.2 Method of measurement with a simulated speech signal 8.2.3 Method of measurement with pink noise 8.2.4 Method of measurement with a sinusoidal signal 8.2.5 Method of measurement with a combi signal 8.2.6 Method of measurement – Other 8.2.7 Requirements |
| 20 | 8.3 Frequency response of the magnetic field 8.3.1 Characteristic to be specified 8.3.2 Method of measurement with a simulated speech signal 8.3.3 Method of measurement with pink noise |
| 21 | 8.3.4 Method of measurement with a sinusoidal signal 8.3.5 Method of measurement with combi signal 8.3.6 Method of measurement – Other 8.3.7 Requirements 8.4 Useful magnetic field volume 8.4.1 Characteristic to be specified |
| 22 | 8.4.2 Methods of measurement 8.4.3 Requirements 9 Small-volume systems 9.1 Definition of measurement points 9.2 Disabled refuge and similar call-points |
| 23 | 9.3 Counter systems |
| 25 | 9.4 Useful magnetic field volume method 9.5 Requirements |
| 26 | 10 Setting up (commissioning) the system 10.1 Procedure 10.2 Requirements 10.3 Amplifier overload at the upper bound of maximum power bandwidth 10.3.1 Explanation |
| 27 | 10.3.2 Methods of test 10.3.3 Requirements |
| 28 | 10.4 Magnetic noise level due to the system 10.4.1 Explanation of term 10.4.2 Method of measurement with a speech signal 10.4.3 Method of measurement with pink noise 10.4.4 Method of measurement with a sinusoidal signal 10.4.5 Method of measurement with a combi signal 10.4.6 Method of measurement – Other (no input signal) 10.4.7 Requirements |
| 29 | Annex A (informative) Systems for small useful magnetic field volumes |
| 32 | Annex B (informative) Measuring equipment |
| 35 | Annex C (informative) Provision of information |
| 37 | Annex D (informative) Measuring speech signals |
| 38 | Annex E (informative) Basic theory and practice of audio-frequency induction-loop systems |
| 47 | Annex F (informative) Effects of metal in the building structure on the magnetic field |
| 49 | Annex G (informative) Calibration of field-strength meters |
| 51 | Annex H (informative) Effect of the aspect ratio of the loop on the magnetic field strength |
| 54 | Annex I (informative) Overspill of magnetic field from an induction-loop system |
| 56 | Bibliography |
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BS EN IEC 60118-4:2015+A1:2018
Electroacoustics. Hearing aids – Induction-loop systems for hearing aid purposes. System performance requirements Published By…
