On distinguishing articulatory configurations and articulatory tasks: Tamil retroflex consonants

Speech production can be described in multiple coordinate frames: articulatory configurations, gestural tasks, and acoustic patterns. Examination of the achievement of retroflex stops and liquids in Tamil suggests that we must consider separately the gestural task of apical post-alveolar constriction and the articulatory maneuver to achieve the task. The maneuver of the tongue during retroflex consonants varies across vowel contexts. Specifically, in the symmetrical intervocalic contexts between back vowels /a/ and /u/, an apical post-alveolar constriction is achieved by curling back the tongue. In the context of high front vowel /i/, a laminal post-alveolar constriction is achieved by bunching the tongue. However, the location of retroflex consonant constriction within the vocal tract is consistent across all of these vowel contexts, suggesting that the constriction task remains the same. Variation in the articulatory configuration of the retroflex in the two contexts was quantified through Gaussian curvature functions at fourteen points along the tongue, sampled at evenly spaced points throughout the vocal tract, on every other gridline of a polar-rectangular grid in every frame in each utterance. The empirical results support the notion that the articulatory configuration coordinate frame and the gestural task frame provide separate, but related, descriptions of speech production.