Summary

This Recommendation specifies the electroacoustical characteristics of artificial ears to be used for telephonometric measurements. Three devices are specified: a telephone band type for measurements on traditional telephone sets, an insert type and a type faithfully reproducing the characteristics of the human ear.

The latter type (Type 3) is specified in four configurations. The requirements of the third one (Type 3.3 � Pinna simulator) have been slightly modified in this revision of ITU-T Rec. P.57 by specifying its construction by a softer elastomer.

Besides this, the description of the applicability of all couplers has been changed, now allowing for an overlap in their usability according to the receiver type under test.