Back From the Future: Nonlinear Anticipation in Adults' and Children's Speech.

Purpose: This study examines the temporal organization of vocalic anticipation in German children from 3 to 7 years of age and adults. The main objective was to test for nonlinear processes in vocalic anticipation, which may result from the interaction between lingual gestural goals for individual vowels and those for their neighbors over time. Method: The technique of ultrasound imaging was employed to record tongue movement at 5 time points throughout short utterances of the form V1#CV2. Vocalic anticipation was examined with generalized additive modeling, an analytical approach allowing for the estimation of both linear and nonlinear influences on anticipatory processes. Results: Both adults and children exhibit nonlinear patterns of vocalic anticipation over time with the degree and extent of vocalic anticipation varying as a function of the individual consonants and vowels assembled. However, noticeable developmental discrepancies were found with vocalic anticipation being present earlier in children's utterances at 3-5 years of age in comparison to adults and, to some extent, 7-year-old children. Conclusions: A developmental transition towards more segmentally-specified coarticulatory organizations seems to occur from kindergarten to primary school to adulthood. In adults, nonlinear anticipatory patterns over time suggest a strong differentiation between the gestural goals for consecutive segments. In children, this differentiation is not yet mature: Vowels show greater prominence over time and seem activated more in phase with those of previous segments relative to adults.