The dynamics of interlip coupling in speakers with a repaired unilateral cleft-lip history.

In this paper, data are presented on individual movement characteristics of the upper and lower lip and on interlip coordination in speakers with a repaired unilateral cleft upper lip history and age-matched control participants. The data were acquired using the AG100 EMMA system while the participants produced a selection of nonspeech and speech tasks. The participants with a repaired unilateral cleft upper lip history showed reduced upper-lip movement ranges and peak velocities and a more variable spatiotemporal pattern for individual upper-lip movement cycles, in addition to a more variable interlip coupling. The latter difference also proved to be more pronounced for the younger speakers with a repaired cleft upper lip. Overall, for both groups, the linguistically more complex task showed more variability in the individual upper- and lower-lip movement cycles and their coupling. In the discussion, we address the potential relationships between the kinematic data for upper lip in the repaired-cleft-lip speakers and the findings on movement and coordination stability as they might fit within current notions of coordination dynamics theory.