Influence of glottal cross-section shape on phonation onset

Abstract

Phonation models commonly rely on the assumption of a two-dimensional glottal geometry to assess kinetic and viscous flow losses. In this paper, the glottal cross-section shape is taken into account in the flow model in order to capture its influence on vocal folds oscillation. For the assessed cross-section shapes (rectangular, elliptical, or circular segment) the minimum pressure threshold enabling to sustain vocal folds oscillation is altered for constriction degrees smaller than 75%. The discrepancy between cross-section shapes increases as the constriction degree decreases.

Validation of an analytical compressed elastic tube model for acoustic wave propagation

“…The transfer function measured on the unflanged case exhibits more prominent maxima and minima than for the flanged case, but otherwise their shape is similar. The difference in amplitude might be due to the lower transmission loss for the unflanged compared to the flanged case since the real part of the radiation impedance is lower for the unflanged case (using (15) and (16) with a=b 0:8) than for the flanged case (using (11) and (12)) for the frequency range considered. The plane wave model applied to the cylindrical unpinched uniform tube geometry fits well the experimental data for both outlet conditions up to the lowest cut-on frequency of about 8 kHz (Table I).…”

“…Human speech production is an example of such a common everyday phenomena for which the channel geometry, i.e., the vocal tract geometry, is crucial for an accurate description of ongoing flow and acoustic phenomena since the vocal tract shape will affect both the flow and the acoustic field. 2,16 Moreover, a rapidly varying channel constriction degree and hence overall channel shape are crucial when considering articulation of phoneme sequences which involves boundary velocities up to hundreds of mm/s and this during several seconds. 12,13 Obviously, a detailed vocal tract channel geometry is extremely complex and is subject to intra-as well as inter-subject differences.…”

“…This favors usage in combination with other analytical model approaches exploiting a limited number of physiologically meaningful input parameters as commonly applied in physical or mathematical speech production models (e.g., Ref. 16 and references therein). A computationally low cost parametrized geometrical tube model is of particular interest when the geometry is rapidly changing such as for a rapid change of the pinching effort, i.e., rapidly and/or consecutive opening and closing.…”