This European Standard is concerned with ear-muffs whose passive acoustic performance may be augmented by an audio communications facility or circuit. It specifies additional constructional, design and performance requirements, methods of test, marking requirements and user information relating to the incorporation of the audio communications facility. The requirements of this standard are intended to take account of the ergonomic interaction between the wearer, the device and where possible the working environment in which the device is likely to be used (see Annex ZA, of this standard and EN 458).