Interaural Discrimination Test

Abstract

Interaural discrimination test using dichotically presented different speech sounds (digits) was investigated for the differential diagnosis of retrocochlear deafness. In this paper, some points to be considered in performing interaural discrimination test were discussed.
The different speech were presented to subjects through a dual-channel tape-recorder with stereophonic ear phones. Each pair of digit sounds was recorded to start as synchronous as possible.
To decide the level presented to subjects, articulation scores of all word-lists were tested. It was most suitable that test words were presented at 40dB above the threshold.
Articulation score of interaural discrimination test was better in hearing the second list than the first list. However, there was no significant difference between the score of the second list and the third list. Then subjects was demanded training only one list beforehand.
This test could be performed without regard to cerebral dominance of hemisphere, because difference of discrimination score between two ears was not detected in normal subjects.
This test was inapplicable to subjects having monaural discrimination loss for digit sounds at 40dB above the threshold.