1. Division of Laryngeal Surgery, Department of Otolaryngology‐Head and Neck Surgery, School of Medicine Jichi Medical University Shimotsuke Japan
2. Department of Otolaryngology‐Head and Neck Surgery, School of Medicine Jichi Medical University Shimotsuke Japan
3. Tokyo Voice Center International University of Health and Welfare Tokyo Japan
4. Department of Otolaryngology Head and Neck Surgery, Faculty of Medicine Yamagata University Yamagata Japan
5. Department of Otolaryngology, Head and Neck Surgery Tohoku University Graduate School of Medicine Sendai Japan
6. Department of Otorhinolaryngology, Head and Neck Surgery, School of Medicine Keio University Tokyo Japan