1986 Volume 89 Issue 6 Pages 706-714
Abrupt high tone loss in perceptive hearing-impaired patients were investigated by means of Bekesy's self-recording audiometry, DLSI test and a Japanese monosyllable speech audiometry. Two new methods were applied for evaluations of DLSI test and the speech audiometry. Statisti-cal observations were made in regard to the cut-off frequencies, the reduction on the amplitude of the continuous tracing and the gradient of steep incline portion by Bekesy's self-recording audiometry. No case showed any abnormal DLSI values which suggested the retrocochlear lesions. Also there was no case showing abnormal low speech cognitive ability indices which were proposed in our previous paper. Therefore, there would be little possibilities of retrocochlear lesions in subjects showing this type of hearing impairment.
Two new methods were also applied to these patients. Comparative study of DLSI value and newly proposed the width of uncertainty in DLSI was carried out in lower and higher frequencies than cut-off frequency. The width of uncertainty in DLSI may represent a part of feature in this type of hearing disorder from the results of this comparative study. Each patient's confusion chart was made by using the speech chart on which each patient's confusion was superimposed and drawn. The tendency of confusion was examined by making the confusion charts according to each cut-off frequency group respectively, and characteristics of confusion were clearly identified. As a conclu-sion, all the results in this study indicated that the main lesion of this type of hearing-impaired patients located at in the inner ear.
