Intraglottal pressures in a three-dimensional model with a non-rectangular glottal shape

Abstract

This study used a symmetric, three-dimensional, physical model of the larynx called M6 in which the transverse plane of the glottis is formed by sinusoidal arcs for each medial vocal fold surface, creating a maximum glottal width of 0.16 cm at the location of the minimal glottal area. Three glottal angles were studied: convergent 10°, uniform ͑0°͒, and divergent 10°. Fourteen pressure taps were incorporated in the upstream-downstream direction on the vocal fold surface at three coronal locations, at the one-fourth, one-half, and three-fourths distances in the anterior-posterior direction of the glottis. The computational software FLUENT was used to compare and augment the data for these cases. Near the glottal entrance, the pressures were similar across the three locations for the uniform case; however, for the convergent case the middle pressure distribution was lower by 4% of the transglottal pressure, and lower by about 2% for the divergent case. Also, there were significant secondary velocities toward the center from both the anterior commissure and vocal process regions ͑of as much as approximately 10% of the axial velocities͒. Thus, the three dimensionality created relatively small pressure gradients and significant secondary velocities anteriorly-posteriorly within the glottis.

Benchmarks for time-domain simulation of sound propagation in soft-walled airways: Steady configurations

“…Assuming that kinetic losses are the same for oscillatory flow as for steady flow (the quasi-steady flow assumption to be discussed later), the data for the M5 model by Scherer et al (2010) can be used to determine the empirical coefficients a m , b d , c m , and b c from pressure distributions in physical models of expansions and contractions. These data do not separate viscous losses from kinetic losses, however.…”

“…The pressure drop at entry is a bit overestimated, but the flow matches. The M5 model of Scherer et al (2010) had entry and exit roundings. At this stage, our area discretization is not fine enough to model the exact nature of the entry and exit roundings, which may account for some of the differences (Scherer et al, 2001).…”

“…(36)- (41) when benchmarks are produced. We used nearly the entire data set of Scherer et al (2010) (nine convergence angles: À40 , À20 shows the pressure profile, dashed lines for the data of Scherer et al (2010) and solid line for our computation [Eqs. (36)- (41)].…”

“…Second, we benchmark bandwidths in terms of viscous losses, radiation losses, and wall vibration losses by comparison to frequency-domain approaches used by Badin and Fant (1984) and Stevens (1998). Third, we introduce a new simulation of kinetic losses based on empirical data by Scherer et al (2010). A subsequent paper will deal with gross dynamical changes of the vocal tract, such as rapid length change and local airway collapse.…”

The effect of entrance radii on intraglottal pressure distributions in the divergent glottis

“…Nonvibratory modeling efforts to measure pressure distributions require the specification of the glottal geometry. This includes, among other details, the degree of glottal adduction (van den Berg et al, 1957), the included glottal angle (the angle between the medial surfaces of the vocal folds) (Gauffin et al, 1983), the slant (obliquity) of the glottis (Scherer et al, 2001a;Shinwari et al, 2003), the anterior-posterior shape of the medial vocal fold surface (Alipour and Scherer, 2000;Scherer et al, 2010), and the curvature of the vocal folds at the glottal entrance and exit locations (Scherer et al, 2001b).…”