ITU-T P.58 PDF

This Recommendation specifies the head and torso simulator (HATS) for telephonometric use. Both sound emissions and sound pick-up characteristics are specified, as well as the free-field acoustic diffraction.

The device is intended for airborne acoustic measurements, and is not suitable for measurements which depend on vibration conduction paths such as bone conduction. The HATS is intended to provide acoustic diffraction similar to that encountered around the median human head and torso and to generate an acoustic field similar to that generated by the human mouth, both in proximity and in the far field.

The methods of use of the HATS in telephonometry are outside the scope of this Recommendation, however the sound pick-up and diffraction characteristics specified by this Recommendation resemble those recommended by the International Electrotechnical Commission (IEC) for the measurement of hearing aids. The electroacoustic measurement methodologies for assessing the performances of hearing aids in their telecommunication applications are then, as far as applicable, as specified by the relevant IEC publications.