Recovery from Temporary Threshold Shift

Abstract

This study reports work in which recovery from Temporary Threshold Shift (TTS) was studied by measuring the time taken for the elevated threshold to recover to normality (i.e. the latent time). It was found that with stimulus frequencies of 1000 and 2000 cps latent time increases as the stimulus intensity is raised from 20 to 60 db, decreases as the stimulus intensity is raised from 60 to 80 db and possibly increases as the stimulus intensity is increased from 80 to 90 db. With 4000 and 8000 cps stimulus frequencies it was found that there is a gradual, negatively accelerating increase in latent time with increasing stimulus intensities. Latent times were found to be maximum at 4000 cps and minimum at 1000 cps and increases in latent time at 4000 and 8000 cps paralleled each other. It is suggested that the results offer indirect evidence that recovery from TTS is diphasic. The author suggests an explanation for the phenomenon based on facilitatory effects within the cochlea.