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Using finite element method for modelling of movement and stress of vocal folds during setting to phonation position
Šíbl, Michal ; Šidlof,, Petr (referee) ; Švancara, Pavel (advisor)
This Master´s thesis deals with use of finite element method for modeling motion and stress of vocal folds during setting to phonation position. The thesis contains a description of the relevant anatomical structures and of the closely related formation of the human voice. A list of some previously published models of the function of human vocal folds follows. A part of my work was to create a model of geometry of the larynx using CATIA V5 and PTC Creo 2.0 on the basis of data acquired by MRI (magnetic resonance imaging). After that the model was converted into the calculation system Ansys Workbench 15.0 and, for solving contact problems, into Ansys Classic 15.0. To solve given problems, these programs use the finite element method (FEM). Solution was carried out for six different variants simulating individual motions of cartilages, corresponding to the activation of individual muscles. For each variant, the movements and stresses in the soft tissue of the vocal folds were evaluated. For variants with activation of IA, TA and LCA muscle it was also evaluated the contact pressure between the vocal folds. Finally, the thesis mentions the preparation of the model for the activation of the vocal folds movement by the muscles of the larynx.
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Influence of Glottal Shape of Human Vocal Fold on its Modal Characteristics
Zelinka, Martin ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
The main goal of the bachelor thesis is to create a parametric model with a variable angle of the human vocal fold and to determine the first two frequencies of vocal fold oscillations for all angles from -40 ° to + 40 °. The result is supported by a review of the anatomy of the human vocal system, the creation and modification of the voice, and current models of the human vocal fold. The model used for this work is created in the 3D CAD Inventor model software. Modal analysis is solved in the computer program ANSYS Workbench, solved using finite element methods.
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Visualization of vocal cords movement
Kutálek, Libor ; Sekora, Jiří (referee) ; Rozman, Jiří (advisor)
The aim of this work is to clarify the function of the vocal cords and get familiarized with their investigative methods. In this work we find possible solutions to the peripheral device to illuminate the rapidly vibrating vocal cords using an LED that is less energy exacting than conventional halogen lamps. Then there are solved the problems of processing, signal filtering and finding the natural frequency of vibration of the vocal cords.
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Development of finite element model of human vocal tract and space around the head based on data from computer tomography
Švarc, Martin ; Pellant, Karel (referee) ; Švancara, Pavel (advisor)
This bachelor´s thesis deals with creating a computational model for acoustic wave propagation in vocal tract and the area near the head. The main objective of this work is to map the three-dimensional model of the human head as an additional acoustic environment for more accurate measurement of the human voice on the basis of data from computed tomography, the study of function of the vocal cords, biomechanics of the human voice and an overview of medical imaging techniques suitable for the display of biomechanical models. The grid for finite element method (FEM) will be created from solid geometry of the vocal tract (from the vocal cords to the lips) and the acoustic space near the human head. The grid will be created in order to obtain new knowledge about the different locations of a human head with microphone.
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Computational modelling of interaction between oscillating vocal folds and air flow
Pavlica, Ondřej ; Matug, Michal (referee) ; Švancara, Pavel (advisor)
Master thesis deals with creating numerical model of the human vocal folds. Calculation algorithm includes interaction between vocal chords and the air flow. Modal analysis of structural and acoustic environment, backround research of vocal folds function and summary of some published overviews of numerical models are parts of this work. Analysis of the results achieved by the numerical simulations and calculations are focused on the pressure and velocity conditions in the areas under vocal folds, between vocal folds and above vocal folds. Movement and stress analysis of individual layers of vocal folds has been made. Impact of tissue thickness on resulting behaviour has been assessed.
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Application of Fluid-structure Interaction on Oscillating Human Vocal Folds
Meisner, Patrik ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
The presented thesis is involved in the biomechanics of phonation. The aim of the thesis is to set a fluid-structure interaction between the vocal folds and air flow when the pressure from lungs reaches the physiological values. In the expected outcome the self-oscillating vocal folds should be observable with characteristics shape-shift from convergent to divergent. In theory part of the thesis is described Anatomy of the vocal tract, physiology of the human phonation, research of computational simulations, experiments and visualisation methods are described in the theory part of the thesis. In the second part, setup of computational simulation with the finite element method is presented. Besides of the fluid-structure interaction the acoustical model is set. Achieved results are presented and compared to the results in literature. Displacements are evaluated from the structural model and pressures, velocities and flow velocities are evaluated from fluid model, so as acoustics results.
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Diagnostical Analysis of Voice
Sala, Pavel ; Šebesta, Vladimír (referee) ; Sigmund, Milan (advisor)
Goal of this work was create survey study of information resources deal with diagnostic analysis of speech signal. Two methods for estimation of glottal flow was programmed. Finally, attention was focused on determination of criterions for description of selected pathological diagnosis and influence of stress on the glottal flow. Outcome of this work is proposal two criterions for describe influence of stress on the glottal flow.
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Computational modelling of human voice propagation through the vocal tract and in space around the head
Švarc, Martin ; Pellant, Karel (referee) ; Švancara, Pavel (advisor)
The following master thesis deals with creating a computational model for acoustic wave distribution by the human vocal tract and then the space around a human head. Detailed mapping of the sound field around the human head is important for more accurate measurement of the human voice. Part of this work is the creation of three-dimensional finite element model of the human head and the vocal tract during phonation of the vowel /:a/ based on the data from the computational tomography. Further the literature search of the function of the vocal tract, biomechanics of the making of the human voice, an overview of the computational models so far published in the literature and in literature reported measurements of the distribution of the human voice by the vocal tract and then in the space around the head . The following is the actual numerical solution of the acoustic waves distribution from the vocal cords through the vocal tract and then the space around the human head when thinking of acoustic absorption on the walls of the vocal tract and on the skin of the head for different types of waking of the model. The results are compared with previously published measurements of the distribution of the human voice and mainly the distortion of the frequency spectra at each specific node in the space around the head and in its vicinity of where the sensor microphones are typically placed are analyzed. Results of the computational modeling will eventually be used for frequency correction for various positions of the microphones scanning the voice distribution in its diagnosis, speech or singing.
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Finite element modelling of pathological changes in human vocal folds tissue and their influence on videokymograph
Martínek, Tomáš ; Matug, Michal (referee) ; Švancara, Pavel (advisor)
Master´s thesis deals with creating planar computational model of human folds, involving fluid-structure interaction. With this model, the influence of changes in vocal folds tissue layers (stiffness, thickness) and their effects on the videokymograph image are studied. Analysis of the results also deals with the evaluation of pressure at selected points below, between and above the vocal folds. The results indicate a possible similarity with the behavior of human vocal folds with pathology. Background research of vocal folds function, an overview of vocal folds pathology and summary of computational models are included.
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