Recommendation ITU-T P.58 specifies the electroacoustic characteristics of head and torso simulators (HATS) to be used for telephonometric measurements. Both the sound generation and sound pick‑up characteristics of these devices are specified.

This revision of Recommendation ITU-T P.58 concerns new distortion and output linearity requirements for the artificial mouth of the HATS (as for Recommendation ITU-T P.51) and describes the positioning on the HATS of the revised Type 3.2 and new Type 3.4 artificial ears.

The artificial ears used in this recommendation support super-wideband as well as full-band applications. It should be noted that the acoustical impedance of the artificial ears has some limitations in realistically simulating human ears.

The artificial mouth used in this recommendation supports super-wideband applications, however it should be noted that the directionality of the artificial mouth is limited in its ability to simulate the human mouth in the super-wideband frequency range.