The effect of glottal angle on intraglottal pressure

Abstract

Intraglottal pressure distributions depend upon glottal shape, size, and diameter. This study reports the effects of varying glottal angle on intraglottal and transglottal pressures using a three-dimensional Plexiglas model with a glottis having nine symmetric glottal angles and a constant minimal glottal diameter of 0.06 cm. The empirical data were supported by computational results using FLUENT. The results suggested that (1) the greater the convergent glottal angle, the greater outward driving forces (higher intraglottal pressures) on the vocal folds; (2) flow resistance was greatest for the uniform glottis, and least for the 10 degrees divergent glottis; (3) the greatest negative pressure in the glottis and therefore the greatest pressure recovery for diverging glottal shapes occurred for an angle of 10 degrees; (4) the smaller the convergent angle, the greater the flow resistance; (5) FLUENT was highly accurate in predicting the empirical pressures of this model; (6) flow separation locations (given by FLUENT) for the divergent glottis moved upstream for larger flows and larger glottal angles. The results suggest that phonatory efficiency related to aerodynamics may be enhanced with vocal fold oscillations that include large convergent angles during glottal opening and small (5 degrees - 10 degrees) divergent angles during glottal closing.

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

“…Although there are small differences, the empirical transglottal pressures support the computational results. The 10 glottal angle condition had the lowest transglottal pressures at each of the entrance radii, followed by 5 , then 20 , 30 , and 40 , supporting the general finding that a diffuser of approximately 10 is the most "efficient" (least flow resistive) (Kline, 1959;Li et al, 2006b).…”

Geometry of human vocal folds and glottal channel for mathematical and biomechanical modeling of voice production

“…From the technical point of view, the vocal fold shape is directly related to the mass distribution in the vibrating elastic element, which influences strongly the vibration eigenmodes (Do¨llinger et al, 2005a;Hora´cˇek et al, 2005;Zhang and Jiang, 2005;Berry, 2001). Besides, vocal folds constitute the channel profile and thus their shape has a dramatic impact on glottal aerodynamics-a small variation of the vocal fold shape or position may change the flow regime and the resulting aerodynamic forces, which excite the system (Li et al, 2006;Thomson et al, 2005;Vilain et al, 2004).…”

An experimental study of the glottal jet

“…Kucinschi et al [4] confronted his Fluent computations with pressure and flow rate measurements on a mechanically driven physical model, but did not assess velocity fields. Li et al [5] used a similar technique (with a static physical model) and tried to evaluate the flow separation points, although only qualitatively. Krane et al [6] made measurements on an externally driven model of the human glottis in a water channel, which operated at lower frequencies.…”