This part of IEC 60118 gives recommendations for the measurement of the performance characteristics of air conduction hearing aids measured with an acoustic coupler or occluded ear simulator.
This part of IEC 60118 is applicable to the measurement and evaluation of the electroacoustical characteristics of hearing aids, for example for type testing and manufacturer data sheets.
This part of IEC 60118 is also applicable for the measurement of the performance characteristics of hearing aids for production, supply and delivery quality-assurance purposes.
For these measurements the frequency range is limited to 5 kHz. The manufacturer can assign nominal values.
The measurement results obtained by the methods specified in this part of IEC 60118 will express the performance under conditions of the measurement and may deviate substantially from the performance of the hearing aid under actual conditions of use.
This part of IEC 60118 primarily uses an acoustic coupler according to IEC 60318-5 which is only intended for loading a hearing aid with specified acoustic impedance and is not intended to model the sound pressure in a person’s ear.
The occluded ear simulator according to IEC 60318-4 may be used for measurements reflecting the output level in the normal human ear. The acoustic coupler according to IEC 60318-8 may be used for extended high frequency measurements and for deep insert hearing aids.
This part of IEC 60118 also covers measurement of hearing aids with non-acoustic inputs, such as wireless, inductive or electrical input.
For the measurement of the performance characteristics of hearing aids for simulated in situ working conditions, IEC 60118-8 is preferred. For measurement of hearing aids under typical user settings and using a speech-like signal, IEC 60118-15 is preferred. According to the requirements in this standard, conformance to a specification is established when measured deviations from design goals do not exceed the corresponding acceptance limits AND the uncertainty of measurement does not exceed the corresponding maximum' permitted uncertainty of measurement for a coverage probability of 95 %.
It is not mandatory to perform all tests contained in this document.
In the case of custom-made in the ear hearing aids, the data supplied by the manufacturer applies only to the particular hearing aid being measured.