1. Division of Laryngeal Surgery, Department of Otolaryngology‐Head and Neck Surgery 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, Faculty of Medicine Yamagata University Yamagata Japan
4. Voice and Dizziness Clinic Futakotamagawa Otolaryngology Tokyo Japan
5. AKASAKA Voice Health Center Tokyo Japan