National Repository of Grey Literature 5 records found  Search took 0.01 seconds. 
On stability of 2D flow-field
Uruba, Václav
Stability of a 2D flow-field generated under 2D boundary conditions will be analyzed using various methods. The most practical cases of such flows are found to be highly instable and thus unphysical. The presented paper analyses the situation with help of experiments and mathematical modelling from literature defining an interesting areas for future experimental research, which could extend the published experimental studies and/or verify some recent results of mathematical modelling.
Influence of the velopharyngeal opening on human voice quality
Vampola, T. ; Horáček, Jaromír
The 3D FE models of the nasal cavities and adult female vocal tract were developed from computer tomography (CT) images for vowels /a:/ and /i:/. The interconnections between the oral and nasal cavities were created according to the anatomical literature. The acoustic frequency - modal characteristics of the FE models were studied by the modal analysis considering zero pressure at the lips and nose and the influence of velopharyngeal insufficiency on the first ten formants was evaluated.
Effect of a soft tissue on vocal tract acoustic resonance properties in vocal exercises using phonation into tubes
Radolf, Vojtěch ; Horáček, Jaromír ; Laukkanen, A. M.
Mathematical model is introduced to clarify the influence of the vocal tract soft tissues on the acoustic resonance (formant) frequencies. The influence is studied in the context of voice therapy technique that uses phonation into tubes. Strong acoustc-structural interaction is demonstrated to take place in the vocal tract when it is prolonged by a tube with the distal end in air or submerged 2 cm and 10 cm in water. The numerical results from the model are compared with the resonance frequencies measured in humans.
Experimental investigation of phonation using artificial models of human vocal folds and vocal tract
Horáček, Jaromír ; Radolf, Vojtěch ; Bula, Vítězslav ; Košina, Jan ; Vampola, T. ; Dušková, Miroslava
The contribution presents results of in vitro measurements of voicing performed on originally developed models of the human vocal folds and vocal tract. The designed models are based on CT and MRI measurements of human subject during phonation. The measured phonation (aerodynamic, vibration and acoustic) chacteristics are comparable with values found in humans.
FE modelling of the influence of the lamina propria properties on the vocal folds vibration and produced sound for specific Czech vowels
Hájek, P. ; Švancara, P. ; Horáček, Jaromír ; Švec, J.G.
The developed two-dimensional finite element model of the flow-induced self-oscillation of the human vocal folds is used for solving fluid-structure-acoustic interaction occurring during phonation. The aim is to nalyze the influence of stiffness of superficial lamina propria on vocal folds vibration considering vocal tracts shaped for the vowels [i:] and [u:].

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