Influence of alterations in the oral environment on speech production.

We examined the influence on temporal aspects of three consonants, /k/, /c/ and /s/, of alterations in the oral environment produced by either palatal augmentation or by an increase in the vertical dimension of occlusion. Voice onset time (V.O.T.) for /k/ and /c/ was influenced more than aspiration time by the palatal augmentation. Consonant duration for /s/ was also influenced by palatal augmentation. Significant influence of an increase in vertical dimension on the timing was not recognized. Speech disorder caused by the malformation of palate seems to be more frequent than that caused by vertical dimension. Adaptation to prostheses would seem to be definitely concerned with orosensory feedback.