1. Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
2. Department of Otorhinolaryngology-Head and Neck Surgery, Hallym University College of Medicine, Seoul, Korea.
3. Department of Audiology, Hallym University, Chuncheon, Korea.
4. Department of Otolaryngology-Head and Neck Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea.
5. Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Medical School, Gwangju, Korea.
6. Department of Pediatrics, Cheil Hospital, Seoul, Korea.