Myoelastic-Aerodynamic Theory of Phonation
Bernoulli principle
According to this principle, a gas such as air passing through a narrow channel increases in velocity and decreased in pressure. The negative pressure between the folds further helps to close them completely by pulling them towards one another.
positive
As the glottis opens due to __________ pressure, the air flowing through the glottis meets the mass of air directly above it, creating compression of the air and increased positive air pressure.
3
Note that for phonation to occur the vocal folds do not have to be completely closed but cannot be father apart than around ____mm.
Bernoulli
Once the folds have been forced apart, they begin to recoil back to the midline due to their *natural elasticity.* As they begin to close, they form a narrow channel. *Second,* the air passing through this construction formed by the closing glottis becomes *negative* in pressure due to the effect of the _________________ principle
natural elasticity
Once the folds have been forced apart, they begin to recoil back to the midline due to their ___________ ____________.
negative
Pressures within the vocal tract immediately above the glottis (supraglottal pressures) also facilitate opening and closing of the glottis during vibration. The air that has already passed through the glottis travels up the *vocal tract.* The distance between the traveling body of air and the glottis increases, resulting in a ___________ pressure directly on the glottis.
vocal tract
The air that has already passed through the glottis travels up the
medial compression
To initiate vocal fold vibration, the vocal folds must adduct to close the glottis. This is achieved by the later cricoarytenoid and interarytenoid muscles, which exert force called...
increase
When the glottis is closed by medial compression the pressure of the air beneath the folds (sub glottal pressure) begins to _________.
apart
When the sub glottal pressure is strong enough, it overcomes the resistance of the closed glottis and forces the vocal folds ________.
self-sustaining oscillator
because vibration continues due to differences in transglottal pressures without an external force needing to be applied for each cycle, the vocal folds are considered to be
vibration
continues for as long as medial compression continues to be exerted, and the interaction between positive and negative air pressures maintains the alternating opening and closing go the glottis.
myoelastic-aerodynamic theory of phonation
describes voice production as an interaction of muscle force (myo), tissue elasticity (elastic), and air pressures and flows (aerodynamics)
PCA
for a voiceless sound or to inhale, the glottis is opened by the _______.
supraglottal positive air pressure
further raises the air pressure within the glottis, creating a stronger opening force.
supraglottal negative pressure
reinforces the negative pressure within the glottis, which facilitates a greater closing force.
duty cycle
the cycle of vibration can be though of as consisting of four phases of vocal fold movement: opening, open, closing, closed.