ITU-T P.57 PDF

This Recommendation specifies the artificial ears for telephonometric use. Three types are recommended, covering the different transducers, types, sizes and technologies.

The methods of use of the artificial ears are outside the scope of this Recommendation; however, some general rules are provided about the application force and the positioning of transducers.

Object

Three types of artificial ears are defined:

1) a telephone-band type for measurements on traditional telephone sets;

2) a type for measuring insert earphones;

3) a type which faithfully reproduces the characteristics of the median human ear.