Persistence of learned motor patterns in speech

It has been noted that “spontaneous” compensations are made during speech for articulatory constraints such as clenching of the jaw. On the other hand, at least several days are required for speech adaptation to a dental prosthesis. A recording of speech and physiological data on jaw activity and tongue contacts was made at the time of initial insertion of an experimental dental prosthesis. Subjects wore the prothesis for two weeks of adaptation, after which a second recording was made, and then waited at least 1 month without experience in speaking with it. A follow‐up recording was then made with the same protocol as when the prosthesis was first inserted. Speech sounded much less disturbed by the insertion of the prothesis after a lapse of a month than it had at initial insertion—knowledge of the compensatory adjustments required had evidently been retained over that period of time. Palatographic data showed a rapid progression toward the compensatory pattern within a few repetitions of the speech sample. [Work supported by NIH.]