Consequences of the change to standards for air-conduction hearing levels. A cautionary note.
The issue of BS 2497 Parts 5 and 6 in 1988 brought British Standards into line with the latest revisions to ISO 389. As a consequence, many audiometers that were previously calibrated using a 9-A coupler will now have to be calibrated with an artificial ear. Whilst this may appear to be a seemless change involving merely alterations to measurement apparatus, this technical note illustrates for two earphone types that it entails a shift in the Hearing Level standard by a maximum of 3 dB at 2 kHz. This has ramifications for longitudinal studies of hearing and for monitoring of hearing threshold levels in persons exposed to noise.
Smith
P A
PA
MRC Institute of Hearing Research, General Hospital, Nottingham, UK.
Lutman
M E
ME
D001299:Audiometry / Q000592:standards*; D001309:Auditory Threshold; D006801:Humans; D012015:Reference Standards