1. Department of Speech and Hearing Sciences, International University of Health and Welfare, and the Voice and Swallowing Center, Fukuoka Sanno Hospital, Fukuoka, Japan
2. Department of Otolaryngology, Graduate School of Medicine, Chiba University, Chiba, Japan
3. Department of Otolaryngology-Head and Neck Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan