Evaluation of Speech Articulation by Motion Capture System and Paratography

Abstract

For the registration of mandibular movements in edentulous subjects, reference points are usually attached on the soft tissue over the chin. Therefore it is extremely beneficial in a clinic to know the relationship of the movement between the skin and the mandibular bone. In this study the reference points on the facial skin that had the least discrepancy with the corresponding sites on the mandibular bone were deteted.
Nine retroreflective markers were placed on the skin over the mandible of dentulous subjects. Furthermore, a marker frame on which 3 markers were arranged spatially was attached to the mandibular teeth of each subject to provide a measured value of virtual points that were indicated by a stick on which 2 markers were aligned. Markers on the facial skin (S) were located and automatically tracked by six video cameras while the mandible was being moved. The measurements of virtual points (V), which were calculated from displacement of the marker frame by using a motion capture system (Vicon 370, Oxford Metrics), were combined with the video data of the markers.
To compare contact patterns of tongue-to-palate and alveolar or maxillary dentures in edentulous patients with and without their dentures, palatograms of edentulous subjects were analyzed with and image processor during the production of sounds.
Artificial palates made of black vinyl covering the palate and alveolar ridge of the maxilla were coated with white alginate powder and inserted into the mouths of the subjects. After pronunciation of the test sounds, the tongue contact areas on the artificial palates were demonstrated by a wetting of the powder and a change in color from white to black. An image processor system was employed for averaging five samples of the same sound for each subject's. The averaged pattern of each subject's palatograms were then converted to the standardized dental arch form, added, and stored. Seventy percent of each subject's common parts were extracted from the combined palatograms of the same sound.