Analysis of Orofacial Movements during Speech by

3 D Motion Capture in Adults with Normal Dentition

Abstract

Orofacial movement trajectories during speech were monitored in 10 dentulous young adults pronouncing the test sentence:[sakura-no-hana-ga-saki-ma∫ita].
Methods: Retro-reflective markers, which were recorded as reflective points with clear outlines when illuminated with infrared strobe lights, were used to provide trajectory data at the following reference points: the modiolus (Mo), menton (Me), vermilion border of lower lip (LL); and incisal point (IP). The facial markers of each subject were located and automatically tracked during pronunciation with the use of six video cameras to provide six different perspectives, and the video data were collected with a data station (Vicon 370, Oxford Metrics). Each time frame during which each consonant was pronounced was identified on the basis of its waveform and sound spectrogram. The movement of each facial target during each time frame was tracked automatically by a work station (Vicon 370), and the three-dimensional (3-D) coordinated data were transferred to a computer. The results of photogrammetric measurement during pronunciation of each tested consonant were analyzed with a 3-D analyzer (Movias 3 D, nac).
Results: Specific trajectories were apparent during pronunciation of [s], [m], and [∫] among other consonants and vowels in the test sentence. The results revealed that mandibular movements (IP) were greater than orofacial movements (Me, LL) during pronunciation of [s]. In contrast, orofacial movements (Me, LL) were greater than mandibular movements (IP) during pronunciation of [m].