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.
Ten experienced tinnitus-masker uses compared four widely different noise bands as potential maskers in a laboratory environment. No reliable individual preferences could be found, and most of the noises were acceptable to most of the subjects. A wide-band noise was marginally most frequently preferred. In this sample, there was no indication that individual tailoring of the frequency spectra of tinnitus maskers is required to achieve acceptable masking. Subjects also underwent tests of hearing, tinnitus matching and tinnitus masking. Most subjects chose noise levels for therapeutic masking that only partially masked their tinnitus. This suggests prescription or trial of tinnitus maskers even for patients who have high minimal masking levels.
Manual and self-recorded audiograms obtained from 240 ears on two occasions 2-3 years apart were compared, with the objective of establishing the preferred method for serial monitoring of hearing thresholds. The self-recording method incorporates an objective scoring algorithm which is compared with subjective scoring carried out independently by two experienced audiology staff members. The objective scoring method agreed well with the subjective method but gives substantial advantages in terms of cost and freedom from scorer bias. The variability associated with manual audiometry was somewhat lower than that associated with self-recording audiometry when used for serial monitoring.
