La coarticolazione e il VOT nello sviluppo fonetico: studio sperimentale su bambini dai 42 ai 47 mesi d'età

In order to study of the acquisition of motor control in the early stages of language development, the empirical analyses preferably rely on acoustic data, as acoustic analysis has the advantage to quantify the phonetic continuum in the time-fequency domain, and at the same time it allows to derive information - by inference - on the movements that produced the phones. The best parameter to quantify and classify the voicing contrast is Voice Onset Time or VOT, which measures the time elapsed since the release of the consonantal occlusion to the beginning of the vibration of the vocal folds. Early in phonetic development, the voiced and unvoiced consonants tend to be realized as voiceless unaspirated, which is the easier articulatory way to achieve synchronization between the glottal and supraglottal events, and only after the acquisition of articulatory maneuvers the kids come to achieve the VOT categories that characterize the native language. The acoustic analysis is also useful for the study of coarticulation, which refers to the temporal overlapping of gestures belonging to neighboring phones. According to the most influential hypothesis, in the development of coarticulation between consonant and vowel in a CV syllable, the child progressively narrows the domain of the articulatory organization from the syllable to the individual C and V gestures, with the consequence of decreasing coarticulation and increasing phonemic distinctiveness. The present study examines the syllables produced by 10 children between the ages of 42 to 47 months, to assess their level of achievement for the VOT and C-V coarticulation. Generally speaking, children are producing a voicing contrast by differentiating the voice-less bilabial and dental consonants, but have some difficulty in the production of sonority for velars. Regarding coarticulation, the present results suggest the existence of two types of evolutionary paths, based on place of articulations (and on coarticulatory strategies rooted in the underlying biomechanical constraints), i.e bilabial vs. velars and dentals.