Sensorimotor adaptation to audito speech: Acoustic and kinem

We investigated sensorimotor adaptation to auditory feedback perturbations during speech production. In Study I, formant or fundamental frequency (F0) feedback was manipulated during sustained vowels. When F0 feedback was altered, group data showed upward F0 adjustments regardless of the feedback shift direction. When formant feedback was altered, group data showed opposing adjustments in both the first and second formant. Sensorimotor adaptation was present at vowel onset, and subjects showed aftereffects when the auditory perturbation was removed. For Studies II (acoustics) and III (kinematics), subjects produced monosyllabic words while upward or downward formant feedback shifts were applied. Acoustic results replicated those for sustained vowels. Kinematic analyses of jaw and tongue positions and displacements indicated motor-equivalent adaptation in the overall gestures rather than individual articulators. Findings are highly consistent with recent data on limb movements and suggest continuous updating of forward and/or inverse internal models of the articulationto-acoustics transformations in the vocal tract.