Npl Report Dql-ac-004 Ii a Review of the Relative Technical and Practical Merits of the Iec Reference Coupler and Artificial Ear and Their Future Role in Pure-tone Audiometry

Pure-tone air-conduction audiometry has become the foundation of hearing assessment. The audiometer, and in particular the earphones used with it, need to be calibrated to ensure measurement traceability. Hearing threshold measurements are then referred to established reference levels to then judge if any hearing loss is present. Ear simulators are used in this process to provide an objective means of determining the sound pressure level presented during a test. At present ISO 389-1 requires the IEC reference coupler to be used for the calibration of a limited number of supra aural earphone configurations and the IEC artificial ear to be used for all other types. In this part of a collaborative project with ISVR, this report suggests that the artificial ear be used universally and shows that users of these devices have responded positively to this recommendation. It thus goes on to propose to ISO that the sole use of the artificial ear and its RETSPL values be the basis for a revision of ISO 389-1. NPL REPORT DQL-AC-004 III  Crown Copyright 2004 Reproduced by Permission of the Controller of HMSO