Two-mass models of the vocal folds and their variants are valuable tools for voice synthesis and analysis, but are not able to produce breathy voice qualities. The produced voice qualities usually lie between normal and pressed. The reason for this property is that the mass elements are aligned parallel to the dorso-ventral axis. Thereby, the glottis always closes simultaneously along the entire length of the vocal folds. For breathy phonation, however, the closure happens rather gradual. This article introduces a modified two-mass model with mass elements that are inclined with respect to the dorso-ventral axis as a function of the degree of abduction. In this way, the closing phase of the glottis becomes progressively more gradual when the degree of abduction is increased. This model is able to produce the continuum of voice qualities from pressed over normal to breathy voices.
Bibliographic reference. Birkholz, Peter / Kröger, Bernd J. / Neuschaefer-Rube, Christiane (2011): "Synthesis of breathy, normal, and pressed phonation using a two-mass model with a triangular glottis", In INTERSPEECH-2011, 2681-2684.