Predicting TT'S for a noise‐exposed population

Abstract

One source of test‐retest variability in serial audiometry is the temporary threshold shift (TTS) caused by prior exposure to sound above 75 dB SPL. In industrial audiometry, TTS is always convolved with the effects of other sources of variability, such as earphone placement, headband tension, instrument calibration, internal physiological noise level, listener criterion, “learning,” etc., as well as with the “true” permanent change in hearing threshold level that is generally the only statistic of interest. However, enough is known about TTS that relatively valid prediction can be made of the mean and standard deviation of the TTS to be expected at test frequency A in an ear with a pre‐exposure hearing threshold level of B dB, measured C minutes after exposure to a noise having spectral characteristics D, level E, duration F, and temporal pattern G. Two propositions will be examined: (1) that this knowledge can be utilized in order to “correct” group audiometric data for TTS, i.e., that TTS can be deconvoluted from the total variance, and (2) that adequacy of use of hearing protection devices can be assessed by means of TTS.