EN IEC 60118-4:2015/A1:2018

FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms and definitions
4 General
5 Using components of a sound system in an induction-loop
   system
6 Meters and test signals
7 Magnetic background noise level of the installation site
8 Characteristics to be specified, methods of measurement
   and requirements
9 Small-volume systems
10 Setting up (commissioning) the system
Annex A (informative) - Systems for small useful magnetic
        field volumes
Annex B (informative) - Measuring equipment
Annex C (informative) - Provision of information
Annex D (informative) - Measuring speech signals
Annex E (informative) - Basic theory and practice of audio-frequency
        induction-loop systems
Annex F (informative) - Effects of metal in the building structure
        on the magnetic field
Annex G (informative) - Calibration of field-strength meters
Annex H (informative) - Effect of the aspect ratio of the loop on
        the magnetic field strength
Annex I (informative) - Overspill of magnetic field from an
        induction-loop system
Bibliography
Annex ZA (normative) - Normative references to
         international publications with their
         corresponding European publications

Defines 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.