I.S. EN 60118-2:1997

1 Scope
2 Object
3 Conditions
4 Explanation of terms
4.1 Automatic gain control (AGC)
4.2 Steady-state input/output graph
4.3 Lower AGC limit or AGC threshold
4.4 Compression ratio (between specified input
      sound pressure level values)
4.5 Dynamic output characteristics
4.6 Attack time
4.7 Recovery time
4.8 AGC activated frequency response
4.9 Operating frequency range of the AGC
5 Steady-state input/output graph
5.1 Graph showing the relation between input sound
      pressure level and output sound pressure level
5.2 Methods of measurement
6 Dynamic output characteristics
6.1 Characteristics to be measured
6.2 Methods of measurement
7 Non-linear distortion
7.1 Transients
7.2 Harmonic distortion
7.3 Intermodulation distortion
8 Effect on steady-state and dynamic performance with
      respect to variation in battery or supply voltage
9 AGC activated frequency response of hearing aids
      with a single channel AGC circuit in operation
      using pure tone signals
Annexes
A (informative) Examples of measuring systems
ZA (normative( Normative references to international
      publications with their corresponding European
      publications

Gives uniform methods for specifying dynamic and static performance characteristics of hearing aids with automatic gain control circuits together with the relevant methods of measurement for these characteristics.