SUBTHRESHOLD AUDITORY ADAPTATION

Abstract

The author observed the abnormal auditory adaptation by using subthreshold stimulus in the subjects with perceptive hearing loss, in which the threshold of the continuous tone was more increased than that of the interrupted tone in fixed rfequency Bekesy audiometry. The experimental procedures were as follows : 1. The measurement of audible time, when the stimulus with the various intensities below the threshold of the continuous tone was presented separately. 2. The changes of the threshold of the conti- nuous tone was observed by using the following different subthreshold auditory stimuli. i. The continuous tone stimuli with increas- ing velocity rate of intensity (5, 2, ldb/sec) in Bekesy audiometry. ii. The continuous tone stimuli started at the intensities of 0db SL, 10db below the inter- rupted tone threshold and 4db below the inter- rupted. The following results were obtained: 1. The subjects was audible for certain se- conds, when the mild intensity below the conti- nuous tone threshold was given separately. 2. No influence on the continuous tone threshold was noticed by using the steady increasing sub- threshold stimuli with increasing velocity rate of intensity (5, 2, ldb/sec). 3, No influence on the threshold of the conti- nuous tone was found by using the steady increasing subthreshold stimuli started at the intensity of Odb SL, 10db below the interrupted tone threshold and 4db below the interrupted. According to these results, the author concluded that in these subjects the gap between the thre- sholds of the continuous and interrupted tone might be the marked abnormal adaptation resulted from steady increasing subthreshold stimulus.