Standard threshold shift criteria. An investigation of the most reliable indicator of noise-induced hearing loss.

Definition of a standard threshold shift (STS) and its use as an early indicator to identify those employees with deteriorating hearing are necessary aspects of hearing conservation programs in industry. STS criteria were evaluated using techniques borrowed from decision theory and signal detection theory to separate audiometric threshold shifts into true-positive and false-positive shifts. The current Occupational Safety and Health Administration definition of a "change in hearing threshold relative to the baseline audiogram of an average of 10 dB or more at 2, 3 or 4 kHz in either ear" and the American Academy of Otolaryngology-Head and Neck Surgery recommendation of a "10 dB or greater change for the worse for either the 0.5, 1, 2 kHz pure tone average or the 3, 4, 6 kHz pure tone average, in either ear" were supported. Revision of baselines after an STS occurs is recommended.