1. Hearing Research Laboratory, Samsung Medical Center, Seoul, Korea.
2. Sungkyunkwan University School of Medicine, Seoul, Korea.
3. Medical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Korea.
4. Department of Otorhinolaryngology-Head and Neck Surgery, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul, Korea.
5. Center for Clinical Epidemiology, Samsung Medical Center, Seoul, Korea.