This document, which is a Technical Specification, describes a head and torso simulator, or manikin, intended for the measurement of air-conduction hearing aids in the frequency range from 100 Hz to 16000 Hz. The manikin described in this document is intended for airborne acoustic measurements only. It is not suitable for measurements which depend upon vibration transmission paths such as bone conduction, or for measurements requiring the simulation of bone or tissue. This document specifies the manikin in terms of both its geometrical dimensions and its acoustical properties. Only manikins compliant with both sets of specifications are in conformance with this document. WARNING - It is acknowledged that devices conforming to this document are used as the basis for applications extending beyond this scope, for example the measurement of sound sources close to the ear or of hearing protection devices. In such cases, it is recommended that any necessary design variations are documented, and that a statistical analysis of the measurement data is carried out to determine the level of repeatability that can be achieved. It will also be necessary to assess the relevance of the measurements made with the head and torso simulator to the application in question.