1. Division of Laryngeal Surgery, Department of Otolaryngology‐Head and Neck Surgery, School of Medicine Jichi Medical University Shimotsuke Japan
2. Tokyo Voice Center International University of Health and Welfare Tokyo Japan
3. Department of Otolaryngology‐Head and Neck Surgery Yamagata University, Faculty of Medicine Yamagata Japan
4. AKASAKA Voice Health Center Tokyo Japan
5. Voice and Dizziness Clinic Futakotamagawa Otolaryngology Tokyo Japan