Applying to headsets, headphones, earphones and earsets intended to be used on, or in, the human ear. Also applies to equipment such as passive networks, pre-amplifiers and power supplies which form an integral part of the headphone system. Specifies the characteristics which should be included by the manufacturer in specifications and relevant methods of measurement. Classification of different types of earphone. Does not deal with: Safety - see reference IEC65[1], characteristics of microphones of headsets - see reference IEC 268-4 [2], earphones and other devices for hearing aids - see reference IEC 118-0 [3], headphones for audiometry; headphones and other devices which form part of an active ear-defender system, although some of its provisions may be applicable.