BS EN 60118-4:2006

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.

Applies 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. The 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.