Tehran University of Medical Sciences Auditory and Vestibular Research 2423-480X 25 2 2016 08 03 127 134 EN Ehsan Negin Department of Audiology, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran Saeid Farahani Department of Audiology, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran Shohreh Jalaie Biostatistics, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran Samaneh Sadat Barootian Department of Audiology, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran Alireza Pourjavid Department of Audiology, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran Maryam Eatemadi Department of Audiology, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran Milad Kazemiha Department of Anatomy, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Mojtaba Barzegar Department of Medical Physics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran 2016 07 02 2016 08 01 Background and Aim: In spite of the effect of the left hemisphere domination on first langu­age acquisition in human, studies suggest activi­ties and the role of both hemispheres in learning second language. Therefore learning a second language requires more communication between the two hemispheres. Regarding the role of the corpus callosum as the only data-centric inter­face between the two hemispheres, the aim of this study was to evaluate and compare the vol­ume of the corpus callosum in monolingual and bilingual individuals. Methods: This cross-sectional study was cond­ucted on 24 samples, 16 simultaneous bilinguals (eight Kurdish-Persian, eight Turkish-Persian) and eight monolinguals with age range of 18 to 30 years, all right handed, and in equal numbers in both sexes (female and male), volume of cor­pus callosum determined by MRI. Data was analyzed by parametric and non-parametric sta­tistical tests. Results: The volume of corpus callosum is sma­ller in monolinguals in comparison with bilin­guals, in which a significant difference was obs­erved (p=0.04). Conclusion: According to the language data transmission and the rate of processing by the corpus callosum between two hemispheres, it seems for improving the quality of aural reha­bilitation, the findings of present study will be useful before performing programs like auditory training, language learning, and by development of neuroplasticity which is often decoded by sti­mulus that occur in the hemisphere in contrast to the dominant hemisphere. https://avr.tums.ac.ir/index.php/avr/article/view/105 https://avr.tums.ac.ir/index.php/avr/article/download/105/50