This part of ISO 8253 specifies procedures and requirements for air conduction and bone conduction threshold audiometry. For screening purposes, only pure-tone air conduction audiometric test methods are specified. It is possible that the procedures are not appropriate for special populations, e.g. very young children. This part of ISO 8253 does not cover audiometric procedures to be carried out at levels above the hearing threshold levels of the subjects. Procedures and requirements for speech audiometry, electrophysiological audiometry, and where loudspeakers are used as a sound source are not specified.