Electropalatographic, acoustic, and perceptual data on adaptation to a palatal perturbation.

Exploring the compensatory responses of the speech production system to perturbation has provided valuable insights into speech motor control. The present experiment was conducted to examine compensation for one such perturbation-a palatal perturbation in the production of the fricative /s/. Subjects wore a specially designed electropalatographic (EPG) appliance with a buildup of acrylic over the alveolar ridge as well as a normal EPG palate. In this way, compensatory tongue positioning could be assessed during a period of target specific and intense practice and compared to nonperturbed conditions. Electropalatographic, acoustic, and perceptual analyses of productions of /asa/ elicited from nine speakers over the course of a one-hour practice period were conducted. Acoustic and perceptual results confirmed earlier findings, which showed improvement in production with a thick artificial palate in place over the practice period; the EPG data showed overall increased maximum contact as well as increased medial and posterior contact for speakers with the thick palate in place, but little change over time. Negative aftereffects were observed in the productions with the thin palate, indicating recalibration of sensorimotor processes in the face of the oral-articulatory perturbation. Findings are discussed with regard to the nature of adaptive articulatory skills.