Ingold Titze, 1988 “The Physics of Small Amplitude Oscillation Theory”
1,What concept is The Small amplitude oscillation theory?
A theory of vocal fold oscillation is developed on the basis of the bodt-cover hypothesis. The cover is represented by a distributed surface layer that can propagate a mucosal surface waves. Linearization of the surface-wave displacement and velocity, and further small-amplitude approximation, yields closed-form expressions for conditions of oscillation. The theory predicts that the lung pressure required to sustain oscillation, i.e., the oscillation threshold pressure, is reduced by reducing the mucosal Wave velocity, by bringing the vocal folds closer together and by reducing the convergence angle in the glottis. The effect of vocal tract acoustic loading is included. It is shown that vocal track inertance reduces the oscillation threshold pressure, whereas vocal tract resistance increases it. The treatment ,which is applicable to falsetto and breathy voice, as well as onset or release of phonation in the absence of vocal fold collision, is harmonized with former treatments based on two-mass models and collapsible tubes.