This part of the standard specifies requirements for construction, design, performance, marking and user information for ear-muffs. In particular, it specifies the sound attenuation of the ear-muffs, measured in accordance with EN 24869-1. This part of the standard does not deal with ear-muffs for attachment to a helmet or which are part of a helmet. Ergonomic aspects are addressed by taking into account, within the requirements, the interaction between the wearer, the device and where possible the working environment in which the device is likely to be used (see Annex ZA and EN 458).