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Abstract:
This study introduced a mechanical model of the larynx for
studying dynamic aerodynamic effects of phonation. The model
mimics the hemilarynx with a rectangular inlet section of 2.5 cm
width and 2 cm height. The glottal constriction was fabricated
with precision machinery from hard plastic with an imbedded
oscillating plunger. The glottal diameter was well specified or
followed by use of a laser system. A speaker assembly, attached
to an audio amplifier, drove the plunger that mimics the glottis.
The transglottal pressure was measured with a well-type wall
manometer. The air was sucked through the channel using a vacuum
with controlled speed. The mean pressure and mean flow data
reported for a rectangular glottal duct varying in frequency and
amplitude. In steady condition, the pressure-flow data was
obtained for the glottal gaps in the range of 0.5 to 2.5 mm. The
result was almost parabolic, following Bernoulli's equation with
a loss factor of about 1.7 for the larger gap and 5.3 for the
smallest gap. In oscillation conditions, either the frequency was
varied from 80 to 160 Hz while the amplitude was almost constant
or the amplitude was varied for the fixed frequency of 100 Hz.
The findings suggest that for this model, the upstream velocity
profiles are almost parabolic and mostly laminar, but downstream
has a turbulent jet with maximum velocity of about 18 m/s located
at 2 mm below the wall.
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