A simulative model of the vocal tract including the effect of nasalization*)

The subject and the aim of this work is the development of an articula-tory model of the speech organ, adapted to computer simulation, for investi-gation of the influence of nasalization due to cleft palate upon the formant structure of originally non-nasal speech sounds, e.g. oral vowels, under realistic operating conditions from the acoustical, physiological and clinical points of view. This was achieved by reproducing the anatomy of the vocal tract under different articulatory conditions including all the possible individual variants, which depend on personal voice characteristics in both normal physiological states and in various pathological conditions. An essential part of the model was the taking into account of the losses in the vocal tract, the radiation impe¬dance of the mouth and/or nose orifice, and the introduction of an additional parameter, which expresses in a quantitative manner the degree of nasalization, depending on the extent of the cleft palate. The model is intended for clinical applications in computer-aided acoustic diagnostics in phoniatry.