Articulatory and temporal aspects of coarticulation in Greek children, adolescents and adults

The issue of variability in speech production is central to theories of speech production and development, as it raises fundamental questions about the nature of speech units and their phonetic instantiations in fluent speech. Various sources give rise to variability in speech, including phonetic context, developmental factors, and coarticulation. Within the framework of articulatory phonology, variability is viewed as a natural consequence of speech organized in terms of overlapping, dynamically coordinated articulatory gestures. Coarticulation, in particular, reflects the temporal organization of gestures and therefore provides a window into the mechanisms underlying speech motor planning and intergestural organization in both mature and in developing speech. The main aim of this dissertation is to examine aspects of temporal and spatial variability in Greek children, adolescents and adults by using acoustic and ultrasound analysis. In particular, we examine the factors that influence segmental duration and lingual coarticulation- both vowel-to-consonant (anticipatory) and consonant-to-vowel (carryover) coarticulation- in 7-year-old children, 14-year-old adolescents and adults. Previous acoustic and articulatory studies in Greek have offered important insight into segmental duration and lingual coarticulation in adult speech (Fourakis, 1986, Nicolaidis, 1997, 2002, Sfakianaki, 2012, Baltazani & Nicolaidis, 2013, Nirgianaki, 2014,), while developmental aspects of speech have been investigated by means of acoustic analysis (Okalidou et al., 2010, Nicolaidis et al., 2019, Kelmali, 2020, Christodoulidou et al., 2023). The present dissertation extends this body of research for Greek by presenting the first ultrasound investigation of lingual coarticulation in children, adolescents and adults. The acoustic analysis showed that segmental duration varies as a function of the articulatory characteristics of the segments, context, gender and age. The ultrasound analysis showed that the degree of anticipatory vowel-to-consonant and carryover consonant-to-vowel coarticulation differed as a function of the articulatory characteristics of the segments across ages. Differences in the degree of coarticulation among children, adolescents and adults were segment-specific, suggesting that the development of coarticulation progresses in parallel with the development of articulatory skills for particular sounds. These findings support the coproduction framework and the Degree of Articulatory Constraint (DAC) model (Recasens et al., 1997), highlighting that coarticulatory patterns are constrained by biomechanical properties of the articulators. In addition, they highlight that coarticulation also reflects the ongoing refinement of speech motor planning during speech development.