Supplementary Material for: An Exploratory Study of the Development of Articulatory Control at the Transition to Speech

This exploratory study aimed to examine changes in motor movements contributing to the development of articulatory control of the primary articulators (jaw, lips, tongue) at the transition from babbling to speech production. This longitudinal study was based on archived recordings of vocalizations of five children, aged nine to 16 months. Vocalizations were phonetically transcribed and these transcriptions were used to determine the sequence of articulatory movements. Results suggest a developmental progression of the level of articulatory control of motor movements such that jaw control emerges first, followed by lip control, while tongue control appears later. Motor control milestones corresponded with developmental shifts in reliable consonant production (VMS) and word learning. The findings suggest a strong association between articulatory control and the emergence of early word production. However, further studies with a larger number of cases are needed to verify this hypothesis. This research line/concept contributes to a more motor-based understanding of speech development and is assumed to have potential implications for early identification and intervention for children with speech and language delays.