The authors have applied the prosthetic treatment to a case of dysarthria caused by the surgical operation for maxillary cancer. The following results were obtained by observing the effects of this treatment through a sonagraph. 1) Patient rehabilitated her articulation remarkably by the prosthetic treatment. 2) Notable rehabilitation were observed on the sound spectrogram of some vowels and consonants such as "i", "e", "w" or "k", "t", "s". 3) Nasalization of vowels still remained in spite of the treatment. This points ont the fact that the prosthetic treatment performed on such case leaves more to be investigated phonetically or acoustically wise.
