Effect of diurnal changes on dichotic listening in younger adults with normal hearing

BACKGROUND: Diurnal changes can be defined as the time of the day over an individual's performance level for different activities that involve physical and mental tasks. OBJECTIVE: The current study aimed to evaluate the effect of diurnal changes in scores obtained for the Dichotic Consonant-Vowel paradigm by young adults with normal hearing sensitivity. METHOD: Based on the ‘Morningness-Eveningness questionnaire’ given by Horne & Ostberg, the subjects were divided into moderately-morning, intermediate and moderately-evening categories. The Dichotic Consonant-Vowel tests were performed during morning and evening, and the right ear, left ear and double correct scores were compared between morning and evening for each category. RESULTS: There was significant diurnal changes noted for moderately morning and evening categories, where morning-type individuals performed better during morning and evening-type individuals performed better during the evening. The scores of intermediate individuals remained unchanged between morning and evening test results. CONCLUSION: Diurnal change is a phenomenon associated with an individual's biological clock mechanism. Hence, attention and inhibitory controls aid them in carrying out tasks that require sufficient physical and mental efforts. The current study suggests that clinicians and researchers consider diurnal changes as an extraneous variable that could affect the reliability of the Dichotic Consonant-Vowel test results.