1. Department of Otorhinolaryngology and Voice Clinic, Tokai University School of Medicine, Tokai University Tokyo Hospital
2. Fukuda Voice Center
3. Department of Speech & Hearing Sciences, International University of Health and Welfare
4. Department of Otorhinolaryngology-Head & Neck Surgery, Kansai Medical University Hirakata Hospital
5. Department of Otorhinolaryngology, Tokai University School of Medicine Tokai University Hospital