scope:

This Recommendation specifies the electroacoustic characteristics of the head and torso simulator (HATS) for telephonometric use. Both sound emissions and sound pick-up characteristics are specified; the free-field acoustic diffraction is also specified.

The device is intended for airborne acoustic measurements, and is not suitable for measurements that 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 lie 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 performance of hearing aids in their telecommunication applications are then, to the extent applicable, specified by the relevant IEC publications.

The characteristics of the device are fully specified for narrowband and wideband speech measurements. Some of its characteristics are described for an enlarged frequency range enabling measurements to be performed for super-wideband speech. Regarding sound pickup, some characteristics are specified up to 20 kHz, thus enabling measurements to be performed for fullband speech as well. Regarding ear simulator acoustic impedance, characteristics are described in [IEC 60318-4] and [ITU-T P.57].