Influence of phonological relevance on top-down and bottom-up processing: a systematic dichotic listening study

Dichotic listening (DL) is a test where auditory stimuli are presented simultaneously to each ear. It is sensitive to hemisphere differences and has been used to study language lateralisation. Recently, dichotic tests have been widely used to study the influence of attention on speech laterality in various disordered populations. The study aims to examine the effect of phonemic relevance on dichotic perception in Kannada. This study was carried out in two phases. Phase 1 aimed to develop and validate a Dichotic word list in Kannada, and Phase 2 involved data collection. Two lists of dichotic pairs were developed and tested with 25 adults across three conditions (free recall, forced right, and forced left). Results showed significant differences in ear responses during the free recall condition, indicating a right-ear advantage. Further, the results showed reduced dichotic performance for phonemically relevant pairs compared to the irrelevant pairs. The findings demonstrated that the right ear advantage can be precisely obtained by increasing the linguistic complexity of dichotic pairs. The addition of phonemic relevance would enhance the clinical utility of dichotic testing for assessing linguistic deficits across various disordered populations.