[Auditory fatigue in man. Comparison of recovery at threshold and above threshold]

Using a 1 000-Hz pure tone, a TTS2 of 20 dB was produced in a group of subjects. Recovery from this TTS was studied at 1 500 Hz and the measurements were extended to 320 min to encompass the course of recovery, The recovery of the temporary impairment of threshold was plotted concurrently with that of the temporary masked threshold shift (TMTS) of the 1 500 Hz tone in the presence of a 700 Hz masking tone. This technique provided an indirect measurement of loudness loss at 10. 20, 30, 40, 50 and 60 dB SL. The time required for complete recovery depended upon whether one measured TTS or TMTS; the longest recovery times were, in respect of the masked threshold, at low sensation levels.