Voice production is governed by the fluid-structure interaction (FSI) that occurs between the airflow coming from
the lungs and the vocal folds, which results in the self-sustained oscillation of the glottis. This vibratory motion is
characterized by opening, closing, and closed phases, and the majority of sound is produced during the mid to
latter closing. Studies have shown that a faster reduction of glottal flow rate (due to increased closing speed or
increased deceleration of the airflow velocity), also known as the maximum flow declination rate (MFDR),
determines the acoustic intensity and the amount of energy in the higher harmonics. Higher harmonics are
important for intelligibility in noise but not in quiet, a major symptom for patients with voice disorders. The glottis
is convergent during opening and divergent during closing. These alternating shapes result in an increase in
intraglottal pressure during opening and a decrease (and possibly negative) during closing, which facilitate
vibrations. Our long-term goal is to ultimately develop a method that enables detailed intraglottal volumetric flow
measurement in a vibrating tissue model of the larynx. This project will advance the method we have developed
for measuring intraglottal flow distribution in a single plane toward measuring the intraglottal volume flow
distribution in a static physical model of the larynx. The proposed work is based on recent advancements we
have made using tomographic particle image velocimetry (tomo-PIV) to capture the dynamics of the volume flow
distribution above the glottal exit11. Toward this goal, our specific aim is: 1) Develop a method for measuring
intraglottal volume flow distribution. Under this aim, we will first demonstrate the intraglottal flow measurement
technique in a static physical model of the larynx. The model's dimensions will be similar to an excised canine
larynx and its static geometry will capture the main features of divergent glottis. We expect to see differences in
the intraglottal vortices and other glottal jet features between the anterior, posterior, and the mid-membranous
aspects of the glottis. We will then validate the intraglottal volume flow measurement technique with auxiliary
flow measurements techniques. We expect to show that the intraglottal flow characteristics (e.g., mean velocity,
turbulence levels and vortical strength) will match the different measurement techniques within 10%.