The
oral and pharyngeal cavities making up the vocal tract undergo
changes in size, shape, and relative proportions during the growth
process from infancy through early childhood and adolescence.
While acoustic theory indicates that vocal geometry is predictive
of the spectrum shape of speech sounds, the relation between
developmental changes in the vocal tract to changes in speech
acoustics has not been adequately investigated. This is due to the
scarcity of quantitative information on the anatomic remodeling of
the vocal tract during development. The goal of this project is to
gain a detailed understanding of the postnatal macroanatomic three
dimensional (3D) development of the vocal tract structures in
typically developing individuals and in individuals with atypical
speech development due to chromosomal aberrations, such as Trisomy
21.
During the past 4 years, we have developed a
head and neck Magnetic Resonance Imaging database (327 typically
and atypically developing cases) and using our established
procedures (Vorperian, et al., 1999) we are making a predefined
set of measurements on 51 structures and have started
developing a unique database of measurements that will permit us
to assess the concurrent development of the head, face and vocal
tract structures. Please visit our
Poster Presentations
page
for some of our current findings.
In the next phase of this project, we
combine imaging, acoustic analysis, and geometric modeling in our
ongoing investigation on the development of the vocal tract from
infancy through adulthood. Our goals are to:
- Expand the
scope of our developmental database by: a) incorporating CT
images in our image database, which is currently based only on
MR images; b) securing a comprehensive set of 2D and a select
set of 3D measurements of vocal tract structures, thus expanding
our measurement database; and c) incorporating the speech
acoustics representative of the specified vocal tract anatomy in
our database by securing a speech sample from a subset of
patients/subjects who are to be imaged.
- Statistically
model general trends in the individual and synchronous growth
patterns of the vocal tract structures.
- Configure
geometric models of the developing vocal tract and compute
formant frequencies; and correlate computed formant values with
age specific acoustic data to make inferences regarding
developmental patterns of articulator mobility.
These goals will be addressed through our MR
imaging database that spans the entire developmental period of
typically and atypically developing cases, and a similar
computerized tomography (CT) image database that we are now
securing. The findings will be of theoretical and clinical
significance for an improved understanding of the anatomic
correlates of speech development.
This research is supported by grants R03
DC4362 and R01 DC 006282 from the National Institute of Health -
National Institute of Deafness and Other Communicative Disorders (NIH-NIDCD).
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