THREE-DIMENSIONAL MODELING OF TONGUE DURING SPEECH USING MRI DATA Sandra Rua Ventura 1 , Diamantino Rui Freitas 2 and João Manuel R. S. Tavares 3 1. ABSTRACT The tongue is the most important and dynamic articulator for speech formation, because of its anatomic aspects (particularly, the large volume of this muscular organ comparatively to the surrounding organs of the vocal tract) and also due to the wide range of movements and flexibility that are involved. In speech communication research, a variety of techniques have been used for measuring the three-dimensional vocal tract shapes. More recently, magnetic resonance imaging (MRI) becomes common; mainly, because this technique allows the collection of a set of static and dynamic images that can represent the entire vocal tract along any orientation. Over the years, different anatomical organs of the vocal tract have been modelled; namely, 2D and 3D tongue models, using parametric or statistical modelling procedures. Our aims are to present and describe some 3D reconstructed models from MRI data, for one subject uttering sustained articulations of some typical Portuguese sounds. Thus, we present a 3D database of the tongue obtained by stack combinations with the subject articulating Portuguese vowels. This 3D knowledge of the speech organs could be very important; especially, for clinical purposes (for example, for the assessment of articulatory impairments followed by tongue surgery in speech rehabilitation), and also for a better understanding of acoustic theory in speech formation. 2. INTRODUCTION The human speech production is a complex and individual mechanism due to the different anatomical structures involved and organs movements implicated. The vocal tract has some important features that are constrained to medical image techniques observation, namely the non-linear shape (similar to a tube L-shaped) and the significant length. Furthermore, the vocal tract organs or articulators change their positions during speech causing shape variation in this tube and subsequently in the air flow. The tongue is the most important and dynamic articulator for speech formation mostly because the large volume of this muscular organ and the wide range of movements and flexibility. For this reason, it is difficult to measure the movements of human tongue and to determine the surface deformation. Many approaches have been used for measuring speech and vocal tract shapes, appearing with very useful results the magnetic resonance imaging. This image technique allows morphologic measurements in static [1-4] and also in dynamic studies [5-9], and can represent the whole vocal tract along any orientation with good soft 1 Professor, Department of Radiology, School of Allied Health Science - IPP, Praça Coronel Pacheco 15, 4050-453 Porto, Portugal 2 Professor, DEEC, FEUP - Faculty of Engineering of University of Porto, Rua Dr. Roberto Frias, s/n 4200-465 Porto, Portugal 3 Professor, DEMEGI, FEUP