15th International Congress of Phonetic Sciences (ICPhS-15)
The unfolding of events in speech ontogeny can be described as the progressive mastering of the degrees of freedom of speech articulators, a process that is to be related to training, imitation, and neural maturation in the child's brain. In this framework, we have shown in previous studies, that canonical babbling, a major step in language development, can indeed be related to the sudden emergence of control over the carrier articulator, i.e. the mandible, in the absence of any other voluntary control over the other speech articulators such as the velum, the lips and the tongue. However if the mastering of mandibular oscillations can be described as the basic carrier structure in speech, this protosyllabic frame will not be adapted to the needs of human adults until the baby is capable of controlling globally its vocal tract from the glottis to the lips, in order to achieve an efficient acoustic intra-syllabic contrast. One element in this global control is that of the velum, which enables to have a fully oral vocal tract, therefore to produce salient consonant-vowel sequences. We have studied the evolution of this control in speech development from an audio-visual digital video corpus of 6 French children. We have been able to show that there is an active control of the velum as soon as 6 months, evidenced by lowering and raising movements during an utterance, and that the proportion of nasal sounds reaches adult norms about 11 months, indicating that a first stage in the mastering of the velum is by that time reached, the next one being the control of nasal vowels.
Bibliographic reference. Lalevée, C. / Vilain, A. (2003): "Development of speech frame control: a longitudinal study of the oral/nasal control", In ICPhS-15, 2003-2006.