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Mass Models of the Vocal Folds under Harmonic Excitation
Řeřuchová, Ivana ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
This bachelor’s thesis belongs to the branch of bioacoustics and biomechanics. It deals with the modelling of simple analytic models of vocal folds, specifically with their forced oscillation caused by a harmonic excitation force. The thesis also includes an anatomy of the respiratory tract and the vocal system, a description of the principal theories of voice production, and an overview of the vocal folds’ mass models.
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Finite element modal analysis of a silicone vocal fold filled with fluid
Hájek, P. ; Radolf, Vojtěch ; Horáček, Jaromír ; Švec, J. G.
A three dimensional (3D) finite element (FE) model of a silicone vocal fold (VF) filled with fluid is presented here. The silicone part of the model is based on partial differential equations of the continuum mechanics and consider large deformations. The fluid domain encapsulated in the silicone VF is defined semianalytically as a lumped-element model describing the fluid in hydrostatic conditions. The elongated and pressurized silicone VF was subjected to perturbed modal analysis. Results showed that the choice of the fluid inside the VF substantially influences the natural frequencies. Namely, the water-filling lowers the natural frequencies approximately by half over the air-filling. Besides, the procedure of reverse engineering for obtaining the geometry of the VF from already 3D-printed mold is introduced.
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Mass Models of the Vocal Folds under Harmonic Excitation
Řeřuchová, Ivana ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
This bachelor’s thesis belongs to the branch of bioacoustics and biomechanics. It deals with the modelling of simple analytic models of vocal folds, specifically with their forced oscillation caused by a harmonic excitation force. The thesis also includes an anatomy of the respiratory tract and the vocal system, a description of the principal theories of voice production, and an overview of the vocal folds’ mass models.
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Automatic analysis of videokymographic images by means of higher-level features
Zita, Aleš ; Zitová, Barbara (advisor) ; Horáček, Jan (referee)
Human voice diagnosis is a complicated problem, even nowadays. The reason is poor access to the body itself and the high frequencies of vocal fold vibrations. One of the clinically available imaging methods to address these problems is Videokymography - a technology for capturing the vocal fold vibrations using a special line CCD camera. Individual lines stacked on top of each other form videokymographic recording. Videokymographic images are suitable for automatic characteristics extraction, therefore helping to reduce the laryngologist workload. For this purpose, the set of such methods is being developed in the Department of Image Processing in the Institute of Information Theory and Automation of the Academy of Science of Czech Republic. The ventricular band position and shape determination is one of the important, but difficult, tasks. The aim of this thesis is to propose new method of automatic detection of ventricular band on videokymographic recording using digital image processing techniques.
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Computational modelling of stress and strain of the human vocal folds during setting up to phonation position
Sádovská, Terézia ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
This master‘s thesis deals with computational modelling of human vocal folds in phonation position using finite element method. There are described larynx anatomy, voice generation theories and overview of so far published computational models of vocal folds. Next part of the paper deals with a redesign of vocal folds and soft tissues‘ geometry, creation of finite element mesh and implementation of active stress in thyroarytenoid muscle. The problem was solved using Ansys 19.2 software. Computation of stress and deformation of soft tissues in phonation position has been made for 7 variations with different combination of active cartilages and muscles. Lastly, there was evaluated an effect of different cartilages and active muscle stress to final stress and deformation of soft tissues of vocal folds.
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Automatic analysis of videokymographic images by means of higher-level features
Zita, Aleš
Human voice diagnosis is a complicated problem, even nowadays. The reason is poor access to the body itself and the high frequencies of vocal fold vibrations. One of the clinically available imaging methods to address these problems is Videokymography - a technology for capturing the vocal fold vibrations using a special line CCD camera. Individual lines stacked on top of each other form videokymographic recording. Videokymographic images are suitable for automatic characteristics extraction, therefore helping to reduce the laryngologist workload. For this purpose, the set of such methods is being developed in the Department of Image Processing in the Institute of Information Theory and Automation of the Academy of Science of Czech Republic. The ventricular band position and shape determination is one of the important, but difficult, tasks. The aim of this thesis is to propose new method of automatic detection of ventricular band on videokymographic recording using digital image processing techniques.
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Computational modelling of mucosal wave propagation in human vocal folds
Vintr, Lukáš ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
The aim of this thesis is to analyze the influence of material parameters of individual layers of vocal cord tissue on the propagation of mucosal waves on the vocal cord model. First, a brief overview of current approaches in experimental and computational modeling of mucosal wave propagation is given on the basis of the literature. Furthermore, the influence of the modulus of elasticity in the tensile epithelium and the surface lamina of propria on the natural frequencies and shapes of oscillations is investigated by means of modal analysis. Mucosal wave propagation was then analyzed using transient analysis in response to the vocal cords to shock excitation by force on the lower part of the vocal cords. The influence of material parameters on the amplitude and speed of mucosal wave propagation over the vocal cord surface was evaluated. In the end of this thesis, the recommendation is given, according to the recorded results, to use lower modulus of elasticity in tension of the surface lamina propria in models with interaction with air flow, because there is much more pronounced mucosal wave propagation corresponding to the behavior of real human vocal cords.
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Modal analysis of vocal folds models with descrete parameters
Lekeš, Filip ; Švancara, Pavel (referee) ; Hájek, Petr (advisor)
Bachelor’s thesis deals with modal analysis of computed models of human vocal folds. It’s about finite element and analytical model where values first eigenfrequencies come under male vocal folds. Research part applies to biomechanics of vocal the human voice, which is followed by an overview of computational models. Finite element model is completely created and solved by ANSYS Workbench commercial program, which uses the finite element method to simulate a problem. Solution of analytical model uses freely available Python programming language. Analysis of the results and comparison of approaches belong to main objectives of the presented work. The proposed analytical model can serve future students for detailed understanding of human vocal oscillations.
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On Finite Element Approximation of Flow Induced Vibration of Elastic Structure
Valášek, J. ; Sváček, P. ; Horáček, Jaromír
In this paper the fluid-structure interaction problem is studied on a simplified model of the human vocal fold. The problem is mathematically described and the arbitrary Lagrangian-Eulerian method is applied in order to treat the time dependent computational domain. The viscous incompressible fluid flow and linear elasticity models are considered. The fluid flow and the motion of elastic body is approximated with the aid of fininite element method. An attention is paid to the applied stabilization technique. The whole algorithm is implemented in an in-house developed solver. Numerical results are presented and the influence of different inlet boundary conditions is discused.
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