Modeling Asymmetrical Movements of Normal and Pathological Tongue (original) (raw)
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Dynamic 3-D tongue model−Progress report
The Journal of the Acoustical Society of America, 1991
An approximate computational model of the tongue including both intrinsic and extrinsic muscles has been constructed based on histological sections of tongue specimens. The tongue is represented by several geometrical solid primitives (blocks) forming local curvilinear coordinate systems, in reference to which muscle fiber directions are specified. Control vertices serve as reference points for each block, and their positional variation allows anatomical scaling. Each block is divided into several finite elements, within each of which fiber directions and muscle activation parameters are computed using linear and quadratic interpolation. The deformation and movement of the tongue is simulated by solving the equations of motion, assuming large deformation and incompressibility of the continuum. A new algorithm has been devised for maintaining deformations isochoric, using a projection method for reduced stress computation. The muscular stresses are computed with a simple model of mus...
Modeling and animating the human tongue during speech production
Computer Animation'94., …, 1994
A geometric and kinematic model for describing the global shape and the predominant motions of the human tongue, to be applied in computer animation, is discussed. The model consists of a spatial configuration of moving points that form the vertices of a mesh of 9 3-D triangles. These triangles are interpreted as charge centres (the so-called skeleton) for a potential field, and the surface of the tongue is modelled as an equi-potential surface of this field. In turn, this surface is approximated by a triangular mesh prior to rendering. As to the motion of the skeleton, precautions are taken in order to achieve (approximate) volume conservation; the computation of the triangular mesh describing the surface of the tongue implements penetration avoidance with respect to the palate. Further, the motions of the skeleton derive from a formal speech model which also controls the motion of the lips to arrive at a visually plausible speech synchronous mouth model.
An Efficient Biomechanical Tongue model for Speech Research
2006
We describe our investigation of a fast 3D finite element method (FEM) for biomedical simulation of a muscle-activated human tongue. Our method uses a linear stiffness-warping scheme to achieve simulation speeds which are within a factor 10 of real-time rates at the expense of a small loss in accuracy. Muscle activations are produced by an arrangement of forces acting along selected edges of the FEM geometry. The model's dynamics are integrated using an implicit Euler formulation, which can be solved using either the conjugate gradient method or a direct sparse solver. To assess the utility of this model, we compare its accuracy against slower, but less approximate, simulations of a reference tongue model prepared using the FEM simulation package ANSYS.
The International Journal of Medical Robotics and Computer Assisted Surgery, 2007
Background In this paper, we study the ability of a 3D biomechanical model of the oral cavity to predict the consequences of tongue surgery on tongue movements, according to the size and location of the tissue loss and the nature of the flap used by the surgeon. Method The core of our model consists of a 3D biomechanical model representing the tongue as a Finite Element Structure with hexahedral elements and hyperelastic properties, in which muscles are represented by specific subsets of elements. This model is inserted in the oral cavity including jaw, palate and pharyngeal walls. Hemiglossectomy and large resection of the mouth floor are simulated by removing the elements corresponding to the tissue losses. Three kinds of reconstruction are modelled, assuming flaps with low, medium or high stiffness.. Results The consequences of these different surgical treatments during the activations of some of the main tongue muscles are shown. Differences in global 3D tongue shape and in velocity patterns are evaluated and interpreted in terms of their potential impact on speech articulation. These simulations have shown to be efficient in accounting for some of the clinically observed consequences of tongue surgery. Conclusion Further improvements still need to be done before being able to generate easily patientspecific models and to decrease significantly the computation time. However, this approach should represent a significant improvement in planning tongue surgery systems and should be a very useful means of improving the understanding of muscle behaviour after partial resection.
Three-Dimensional Modeling of Tongue During Speech Using Mri Data
2000
1. ABSTRACT The tongue is the most important and dynamic articu lator for speech formation, because of its anatomic aspects (particularly, the large vo lume of this muscular organ comparatively to the surrounding organs of the voca l tract) and also due to the wide range of movements and flexibility that are involve d. In speech communication research, a variety
Use of a Biomedicanical Tongue Model to Predict the Impact of Tongue Surgery on Speech Production
2007
This paper presents predictions of the consequences of tongue surgery on speech production. For this purpose, a 3D finite element model of the tongue is used that represents this articulator as a deformable structure in which tongue muscles anatomy is realistically described. Two examples of tongue surgery, which are common in the treatment of cancers of the oral cavity, are modelled, namely a hemiglossectomy and a large resection of the mouth floor. In both cases, three kinds of possible reconstruction are simulated, assuming flaps with different stiffness. Predictions are computed for the cardinal vowels /i, a, u/ in the absence of any compensatory strategy, i.e. with the same motor commands as the one associated with the production of these vowels in non-pathological conditions. The estimated vocal tract area functions and the corresponding formants are compared to the ones obtained under normal conditions.
Journal of Phonetics, 2002
In this study, previous articulatory midsagittal models of tongue and lips are extended to full three-dimensional models. The geometry of these vocal organs is measured on one subject uttering a corpus of sustained articulations in French. The 3D data are obtained from magnetic resonance imaging of the tongue, and from front and profile video images of the subject's face marked with small beads. The degrees of freedom of the articulators, i.e., the uncorrelated linear components needed to represent the 3D coordinates of these articulators, are extracted by linear component analysis from these data. In addition to a common jaw height parameter, the tongue is controlled by four parameters while the lips and face are also driven by four parameters. These parameters are for the most part extracted from the midsagittal contours, and are clearly interpretable in phonetic/biomechanical terms. This implies that most 3D features such as tongue groove or lateral channels can be controlled by articulatory parameters defined for the midsagittal model. Similarly, the 3D geometry of the lips is determined by parameters such as lip protrusion or aperture, that can be measured from a profile view of the face. r