1. Department of Clinical Support, Division of Rehabilitation, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan
2. Department of Otorhinolaryngology, Head and Neck Surgery, Hiroshima University Hospital, 1-2-3, Kasumi, Minami-ku, Hiroshima 734-8551, Japan
3. Institute of Science and Engineering, Faculty of Frontier Engineering, Kanazawa University, Kanazawa 920-1192, Japan