Comparison of functional asymmetry of cerebral hemispheres in dichotic listening between elderlies and young adults

Background: Evidences suggest that representation of language information in the brain changes with increasing age and this reduces the dichotic auditory function in the elderlies. The aim of the present study was a comparison between functional asymmetry of cerebral hemispheres in dichotic listening of elderlies and young adults by using dichotic consonant-vowel and digit tests. Materials & Methods: This cross- sectional study was performed on 28 right-handed young healthy people aged 18 to 28 years and 27 elderlies aged 60 to 80 years using Persian version of the dichotic consonant-vowel and digit tests. The results of right and left ears were compared in non-forced attention (NF), forced right (FR), and forced left (FL) attention conditions. Results: Comparison of dichotic digit test results in divided attention condition showed significant difference between two age groups (p-value=0.001). Comparison of dichotic consonant-vowel test results in non-forced attention condition showed no statistically significant difference in right ear for correct scores between two age groups (p-value=0.97), but the difference was significant (p-value=0.001) in left ear. Also, in forced right (FR) and forced left (FL) conditions, there were significant differences for correct scores in both ears between two age groups (p-value=0.001).Conclusion: The results of this study confirmed functional deterioration in the elderlies particularly in forced left attention condition. Old subjects showed greater hemispheric asymmetries and lower accuracy in the scores obtained in two tests.

Comparison of functional asymmetry of cerebral hemispheres in dichotic listening between elderlies and young adults Keywords:

aging , dichotic consonant-vowel test , dichotic digit test , auditory divided attention , focused attention