This part of IEC 60318 describes a head and torso simulator (manikin) intended for the measurement of air-conduction hearing aids in the frequency range from 100 Hz to 10 000 Hz. The device consists of a head mounted on a torso that extends to the waist. The head is equipped with simulated pinnae and with cylindrical cavities having acoustic impedance terminations and microphones located at positions corresponding to those of the eardrums in a median human adult. It has been designed to provide acoustic diffraction similar to that encountered around the median human head and torso. The device with its present pinna simulator@ however@ is not suitable for the measurement of all types of hearing aids. For example@ most in-the-ear (ITE) and completely-in-the-canal (CIC) hearing aids cannot be measured correctly. The manikin is specified in terms of both@ its geometrical dimensions and its acoustical properties. NOTE 1 Measurement results obtained with a manikin may differ substantially from similar results obtained on an individual person@ due to anatomical variations. NOTE 2 The median values of the human head and torso were drawn from the population samples described in [5]1. NOTE 3 It is acknowledged that devices conforming to this part of IEC 60318 are also used as the basis for applications extending beyond this Scope. In such cases it is recommended that any design variations that are necessary are documented@ and that a statistical analysis of the measurement data be carried out to determine the level of repeatability that can be achieved. It will also be necessary to consider the relevance of the measurements made with the head and torso simulator to the application in question.