ALSO NUMBERED AS BS 6840 PT7 1996 Applicable to headphones, headsets, earphones and earsets for use on or in the human ear. Also describes pre-amplifiers, passive networks and power supplies forming an integral part of the headphone system. Not applicable to safety, characteristics of microphones of headsets, earphones and other devices for hearing aids, headphones for audiometry and headphones and other equipment forming part of an active ear-defender system.