Vocal fold geometry plays an important role in human phonation. The intraglottal quasi- steady pressure and velocity distributions depend upon the shape, size, and diameter of the glottis. This study reports the effects of the variation of glottal shapes on intraglottal pressures and velocities using a Plexiglas model with a glottis having nine symmetric glottal angles (uniform, as well as con-vergent and divergent 5°, 10°, 20° and 40°), while the minimal glottal diameter was held constant at 0.06 cm. The empirical data were supported by penalty finite element computational results. The re-sults suggest that larger convergent glottal angles correspond to increased pressures and decreased velocities in the glottis upstream of the minimum glottal location, with a reversal of this pattern at the minimal glottal diameter location. The pressure dip near the glottal entrance for divergent glottal an-gles was greatest for the 10° divergence angle condition, and was sequentially less for 5°, 20°, and 40°. Flow resistance was greater for a convergent angle than a divergent angle of the same value, and least for the 10° divergent condition. Pressure recovery in the glottis suggested that the optimal glottal diffuser angle was near 10°. Results suggest that the glottal geometry has a critical relationship with phonation (especially for vocal efficiency), and therefore important significance to understanding artistic voice and clinical voice management. Vocal fold geometry plays an important role in human phonation. The intraglottal pressures and velocity distributions depend upon the shape, size, and diameter of the glottis. This study reports the effects of the variation of glottal shapes on intraglottal pressures and velocities using a The Plexiglas model with a glottis having nine symmetric glottal angles (uniform as well as con-vergent and divergent 5 °, 10 °, 20 ° and 40 °) while the minimal glottal diameter was held constant at 0.06 cm. The empirical data were supported by penalty finite element computational results. The re-sults suggests that the larger convergent glottal angles correspond to increased pressures and decreased velocities in the glottis upstream of the minimum glottal location, with a reversal of this pattern at the minimal glottal diameter location. The pressure dip near the glottal entrance for divergent glottal an-gles was greatest for the 10 ° divergence angle condition, and was sequentially less for 5 °, 20 °, and 40 °. Flow resistance was greater for a convergent angle than a divergent angle of the same value, and least for 10 ° divergent condition. Pressure recovery in the glottis suggested that the optimal glottal diffuser angle was near 10 °. Results suggest that the glottal geometry has a critical relationship with phonation (especially for vocal efficiency), and therefore important significance to understand artistic voice and clinical voice management.