1. 1) F. Darley, A. Aronson and J. Brown, Motor Speech Disorders (W. B. Saunders, Philadelphia, London, Toronto, 1975), p. 2.
2. 2) K. M. Yorkston, "Treatment efficacy: Dysarthria," J. Speech Hear. Res., 39, 46–57 (1996).
3. 3) M. Kariyasu, T. Matsuhira and M. Toyama, "Communication disorder and estimated number of persons with disability," Dep. Bull. Pap., Kyoto Gakuen Daigaku Sogo Kenkyujo Shohou, 18, 55–60 (2017) (in Japanese).
4. 4) A. Toyota, "Actual status of stroke in the working generation based on patient statistics of rosai general hospitals in Japan," J. Occup. Med. Traumatol., 58, 89–93 (2010) (in Japanese).
5. 5) L. Ramig, C. Mead, R. Scherer, Y. Horii, K. Larson and D. Kohler, "Voice therapy and Parkinson's disease: A longitudinal study of efficacy," Paper presented at the Clinical Dysarthria Conf., San Diego, (1988).