Analysis of tongue trajectory variation for /r/ in older children and adults

Abstract

Kinematic studies of tongue articulator movement have found that older children and adolescents have smaller articulator displacements and greater movement variability compared to adults. However, many of these kinematic studies have used simple, early-developing phonemes as stimuli for comparison across talker groups. The American English rhotic /r/ is the latest to be acquired in children, possibly due to the complexity of the pharyngeal and oral constriction pattern required to produce the sound. In this study, we use automated processing of midsagittal ultrasound images to track trajectories of tongue blade, dorsum, and root during /r/ production in older children and adults. Our preliminary results suggest that the trajectories of tongue parts are different for adults and children, with children producing tongue part movements with greater relative amplitude and variability. We explore the possible developmental reasons for this outcome through the lens of dynamic principles of stability and change.