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Abstract:
This paper used a newly developed technique, tagged
Cine-Magnetic Resonance Imaging ( tMRI), to examine the internal
deformation of the tongue during speech. Two studies, each on a
single subject, examined local internal tongue motion in 2D and
3D. The first study examined the motion of approximately 40
points within the tongue, in each of three sagittal slices (L, M,
R), tracked during the movement from /k/ to /a/. Measurements of
tag positions were made at 7 consecutive time-phases in the
syllable. A mechanical model of tongue deformation, similar to a
finite element analysis, calculated local homogeneous stretch
based on the deformations of the tag points between the consonant
and vowel. 110 internal tongue locations were probed and
principal strains were calculated for them using the model. The
principal strains revealed local compression and extension
patterns from which inferences could be drawn about the
activities of Verticalis, Hyoglossus and Superior Longitudinal
muscles. The second study tracked 3D motion and calculated 3D
strains from multiplanar tMRI images, for the syllable "sha".
Three orthogonal tag planes (x, y, z) were collected for 24
consecutive time-phases in 10 axial and 5 sagittal slices. The
sagittal slices were recorded twice, once each with horizontal
and vertical tag planes. The axial slices were recorded once with
lengthwise (anterior-to-posterior) tag planes. These planes
reflect deformations in y, z and x respectively. A B- spline
model tracked tag deformation in each plane and reconstructed 3D
deformation. This model is being adapted from cardiac tagging
methods and preliminary data are presented.
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