Intraglottal pressures related to glottal and laryngeal asymmetries

The air pressures within the glottis during phonation may be highly dependent upon the symmetry of the glottis and other laryngeal structures. Physical laryngeal models M5 and M6 have been used to explore the slanted “oblique” glottis with different included and oblique angles, the change to three dimensions, and the presence of the arytenoid cartilages. Results suggest that (1) the greater the oblique angle, the higher the glottal entrance pressures compared to the symmetric glottis, (2) the larger the intraglottal angle, the more different the pressures are on the two glottal sides, (3) pressures are higher on the convergent side than on the divergent side of the glottis, (4) intraglottal pressure depends on which side of the glottis the flow exits, with the Flow Wall side having lower pressures, (5) for large glottal diameters, all intraglottal pressures may be lower on the Flow Wall side, (6) for special cases of high transglottal pressure, the pressure near glottal exit may be lower than at entrance (divergent glottis), (7) a symmetric but 3-dimensional glottis has consistent but minor pressure changes in the anterior-posterior direction, and (8) the presence of the arytenoid cartilages has minor effects on the intraglottal pressures. [Support from NIH.]