the respective vowel sounds.
While the sound source (glottal flow) produced by
vocal fold vibration may appear to be relatively simple,the
mechanisms responsible for inducing and sustaining the
vibration involve complexities of anatomy,muscular
control,nonlinear flow-induced oscillation,and the interaction
of vocal tract pressures with both the glottal flow
and the movement of the vocal folds themselves. To show
how some of these complexities are integrated with vowel
production this paper has three aims: (1) to review the
anatomical structure of vocal folds and their vibratory
kinematics,(2) to present a brief overview of vocal fold
modeling,and (3) to use a low-dimensional model to
illustrate some basic mechanisms of vocal fold oscillation,
including the acoustic interaction with the vocal tract.
2. VOCAL FOLD STRUCTURE AND
VIBRATORY KINEMATICS
The vocal folds are soft tissue structures contained
within the cartilaginous framework of the larynx. Their
location in the neck and their ability to abduct (move apart)
during respiration and to adduct (move together) during
phonation makes the vocal folds the point of division
between the subglottal and supraglottal airways. Four
views of the larynx and vocal folds are shown in Fig. 2.
The first is a midsagittal sketch of the head and neck
indicating the location of the larynx (Fig. 2a) and the
second is a schematic drawing showing how the vocal folds
are located at the superior end of the trachea and connected
to the lower portion of the pharynx (Fig. 2b). During