Articulatory–acoustic relationships during vocal tract growth for French vowels: Analysis of real data and simulations with an articulatory model

Abstract

This paper reports on the articulatory–acoustic relationships involved during vocal tract growth. Data were taken from a database of ten French vowels uttered by 15 speakers ranging in age from 3 years old to adulthood. Despite the important acoustic variation encountered, one feature is displayed by all the speakers: the production of extreme focal vowels /i/, /u/, /a/, and /y/, realized with a strong concentration of spectral energy related to the proximity of two formant peaks. This feature represents an acoustic goal guiding the speaker's task. Our simulations using an articulatory model demonstrate that the realization of the focalization feature may require different articulatory gestures for young children compared to adults, consisting of adaptive articulatory strategies exploited to compensate for the small pharynx of the former. Perceptual tests show that achieving focalization results in a lower intelligibility for the children than for the adults. Due to the relatively shorter pharyngeal cavity of the child compared to the adult, focalization cannot be achieved together with the perceptual objective related to rounded vowels /y/ in French. Results are discussed in light of the dispersion-focalization theory and the perception for action control theory (PACT).