scope:

This standard describes test methods which include the acoustical effects of a simulated median adult wearer on the performance of a hearing aid.

Measurements described in this standard made under simulated real-ear aided working conditions are divided into two classes:

• Direct simulated real-ear aided measurements, which determine the sound pressure developed by a hearing aid in an ear simulator for a given free-field input sound pressure.

• Insertion measurements, which determine the difference between the sound pressures developed in the ear simulator with and without a hearing aid in place.

Such measurements attempt to determine the actual acoustical assistance that a hearing aid gives to a user. The results obtained under simulated real-ear aided conditions may differ substantially from results obtained on an individual person due to anatomical and physiological variations of heads, torsos, pinnae, ear canals, and eardrums.

The methods in this standard give information on the measurement of the following parameters that are considered important for the evaluation of the performance of a hearing aid as normally worn, and for which simulated real-ear aided conditions are considered essential:

• insertion gain

• real-ear aided output sound-pressure level for 90 dB input sound-pressure level

• directional characteristics

The measured quantities described in this standard are, in general, functions of frequency and elevation and azimuth angles of sound incidence unless otherwise specified.

The test methods described in this standard are conducted with hearing aids set in linear, non-adaptive, mode, unless otherwise stated.

The test methods described in this document are not intended for quality control.