Development, and validation of non-speech dichotic listening test

Background:Classic dichotic listening tests using speech stimuli result in right ear advantage,due to the dominant crossed pathway for speech and language.It is presumed that similar crossed dominance could exist for non-speech stimuli too.Hence,this is an attempt to develop and validate the dichotic nonspeech test using environmental stimuli and explore the effect of focused attention on this test.Materials and method:Three lists of dichotic stimuli were created using these sounds with fifteen tokens in each list.Four professionals and non-professionals validated these materials.Normative estimation was obtained by administering the newly developed test on 70 adults and 70 children using a free-recall and forced-recall condition.Result:The results showed a significant difference between the left ear and right scores where the left ear score was better than the right,depicting left ear advantage(LEA)for free recall condition in both groups.In the forced recall condition,LEA was not seen;rather the mean score was significantly higher in the attended ear,irrespective of the stimuli presented to the right or left ear.The test-retest reliability in free recall was good in both the ears and moderate for forced right ear conditions.Conclusion:The novel test consistently showed LEA with good reliability and can be used to assess the hemispheric asymmetry in normal subjects and also in test batteries for the clinical population.

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.