Recovery from Temporary Threshold Shifts as a Function of Test and Exposure Frequencies

The purpose of these experiments was to test Ward's hypothesis that recovery time is a function of the initial loss and independent of test frequency and to extend his findings to higher test frequencies. Twenty-five subjects were exposed to 110-dB sinusoidal stimulation at 700, 2700, and 8000 Hz at varying durations so as to produce approximately equal (within-5-dB) losses (10–30 dB) at one of 13 test frequencies ranging from 250 to 12 000 Hz. Recovery was followed until thresholds had returned to within 5 dB of the pretest levels. The results indicated that subjects took significantly more time to recover from high-frequency than from low-frequency exposures. The analysis is still in progress, but these results suggest that recovery from high-frequency sinusoidal exposure is slower than recovery from low-frequency sinusoidal exposure.