1. Skull base Research Center, Loghman Hakim Hospital, Shahid Beheshti University of Medical Sciences, Tehran 19839-63113, Iran
2. Department of Epidemiology, Faculty of Health, Mashhad University of Medical Sciences, Mashhad 13131-99137, Iran
3. Centre for Research in Neuroscience, The Research Institute of the McGill University Health Center, 1650 Cedar Ave., Montreal, Quebec H3A 1A1, Canada
4. Department of Epidemiology, School of Public Health, Iran University of Medical Sciences, Tehran 14496-14535, Iran
5. Hearing Disorders Research Center, Shahid Beheshti University of Medical Sciences, Tehran 19839-63113, Iran