Abstract
In the approach to clarify the central auditory pathway by the temporal aspect, auditory and visual response times were measured as a means of elucidating various auditory phenomena caused by dysacusia of central origin. Subjects examined were the patients with hemiplegia due to cerebrovascular disorder and normal volunteers having no hear loss except physiologial changes attributable to aging.
The subjects were instructed to switch on just as soon as they perceived auditory and visual stimuli delivered to them (tapping) . The results of the testing with statistical analyses of data are summarized as follows : Normal subjects : 1) The auditory response time was 293msec with biaural hearing, which was shorter than a corresponding value with monoaural hearing of 323-326msec. 2) The visual response time, regardless of whether binocular or monocular sight, was between 277 and 279msec. 3) There was no significant difference between auditory and visual response time values. Hemiplegic patients : 1) Auditory and visual response times measured in all tests were significantly prolonged by 100-150msec as compared to the normal group. 2) Whilst little differences were observed between the right and left sides in auditory and visual response times, the auditory response time was prolonged with right ear hearing as compared with left ear hearing in patients with right hemiplegia. 3) Even though differences between visual and auditory response times hardly attained statistical significance if present at all, a significant difference was noted between auditory response time with right ear hearing and visual response time with right eye sight in patients with right hemiplegia. Through these findings and based on the neurological considerations on auditory and visual paths, it is warranted to assume that the observed prolongation of auditory response time might be related to an injury to the path connecting between the superior colliculus and the Heschl's gyrus.
