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Modelování vibračních vlastností lidských hlasivek
Vampola, T. ; Horáček, Jaromír ; Klepáček, I.
A 3D finite element model of the human larynx including the vocal folds was developed. The model enables to take into account phonation position (tinsion and adduction) of the vocal folds by positioning of the arythenoid and thyroid cartilages. Anisotropic properties of the three layers of the vocal fold living tissue (epitel, ligament and muscle) are modelled respecting the material nonlinearities with increasing prolongation of the tissue in longitudinal direction. The motion of the vocal folds is numerically simulated for a prescribed subglottal pressure loading the vocal folds by a periodic function in the time domain. the generated motion of the vocal folds seems to be qualitatively similar to a vibration mode known from clinical measurements.
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Možnosti ladění a optimalizace akustických rezonančních vlastností vokálního traktu člověka
Radolf, Vojtěch ; Vampola, T.
The paper deals with optimization process finding such geometrical form of acoustical cavities of the human supraglottal spaces which leads to excitation of predefined acousic resonance, especially between a domain of the third and the fifth formant. The problem is solved by the transfer matrix method using conic acoustic elements for the vocal tract modelling and numerical method of searching a minimum of a goal function of several variables. The results should help to obtain a physical background for voice rehabilitation, for teaching of opera singers at musical facuoties and for better understanding of biomechanics of voice production.
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Influence of velopharyngeal insufficiency on phonation of Czech vowels
Vampola, T. ; Horáček, Jaromír
The effects of velopharyngeal insufficiency on acoustic frequency-modal characteristics of human supraglottal spaces are investigated. The finite element model was developed from magnetic resonance images (MRI) of the subject during phonation. The influence of the velopharyngeal insufficiency on phonation of the Czech vowels /A,I,U/ is numerically simulated in time domain. The Liljecrants-Fantś pulse is used for excitation of the acoustic system.
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1D model of the human vocal and nasal tract
Radolf, Vojtěch ; Vampola, T. ; Horáček, Jaromír
The paper deals with use of the transfer matrix method to determine acoustic characteristics of the human vocal tract connected with the nasal tract. The system models the influence of velopharyngeal insufficiency on production of Czech vowel /a/. The advantage of this method is significant shortening of the computing time compared to computations with 3D FE method. The model of the acoustical spaces is created by cylindrical elements. The calculation is carried out for periodic "L-F" signal applied at the position of glottis. Time dependent acoustic pressure and air flow volume velocity at the position of the lips and nose are computed. The resulting frequency response functions of the tract are compared with computations realized by 3D FE model.
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Volumetric model of human vocal folds
Vampola, T. ; Horáček, Jaromír
The article describes the vollumetric 3D FE model of real human vocal folds in a defined phonation position. The model was developed from the CT images of the plaster casts obtained by a special procedure during experiments with the excised human larynges, when the phonatioon caused by the airflow was suddenly stopped without changing the position of the fixed larynx. The model is determined for studies of dynamical stresses in the vocal fold tissue during vocal folds collisions.
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