British Journal of Disorders of Communication. 26(1):11-23, 1991 Apr.
Abstract
The internal structures of the vocal tract are difficult to measure
without impinging upon their normal movement patterns. Imaging techniques
overcome that difficulty because they measure internal movement
indirectly, without direct contact with the structures. This paper
examines four well-known imaging techniques: X-ray, computed tomography
(CT), magnetic resonance imaging (MRI) and ultrasound. Tongue and vocal
tract researchers have employed all of these techniques. Imaging systems
provide very different articulatory information from flesh point tracking
systems. They provide information about the shape and position of the
entire imaged structure, rather than a single point on the structure. In
addition, images usually can be made in multiple planes, providing
midsagittal, parasagittal, coronal, transverse and oblique sections of the
structure. However, these systems have several limitations. CT and MRI
create static images only. Ultrasound cannot image hard tissue. Radiation
exposure limits the duration of X-ray imaging. This paper discusses the
advantages and limitations of imaging systems, as well as the uniqueness
of the measurements made with them.
