  An inverse scattering problem is analyzed for vowel articulation in the human
vocal tract. When a unit amplitude, monochromatic, sinusoidal volume velocity
is sent from the glottis towards the lips, various types of scattering data are
used to examine whether the cross sectional area of the vocal tract can
uniquely be determined by each data set. Among the data sets considered are the
absolute value of the pressure measured at a microphone placed at some distance
from the lips, the pressure at the lips, and the transfer function from the
glottis to the lips. In case of nonuniqueness, it is indicated what additional
information may be used for the unique determination.
