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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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Numerical Solution of 3D Airflow in Channel Representing a Vocal Tract
Pořízková, P. ; Kozel, Karel ; Horáček, Jaromír
This study deals with the numerical solution of a 3D compressible flow of a viscous fluid in a channel for low inlet airfloe velocity. the channel is a simplified model of the glottal space in the human vocal tract. The system of Navier-Stokes equations has been used as mathematical model of laminar flow of the compressible viscous fluid in a domain. The numerical solution is implemented using the finite volume method (FVM)and the predictor-corrector MacCormack scheme with artifical viscosity using a grid of quadrilateral cells.
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Analysis of the influence of piriform sinus on vocal tract acoustic characteristics
Radolf, Vojtěch
An analysis of several testing mathematical models and human vocal tract model with piriform sinus (PS) cavities was done. The method used was based on 1D acoustic wave equation, considering viscous losses, radiation impedance losses and applied on conical elements in frequency domain. The analysis revealed that the 1D model is able to capture differences in acoustic variables of the vocal tract modified with PS. Nevertheless the model includes PS of very small dimensions (9 mm in depth) that generate spectral changes far away from frequency band 4-5 kHz as Dang&Honda (1996) observed with their models including PS up to 20 mm in depth.
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1D modeling of the influence of velopharyngeal insufficiency on phonation of vowels
Radolf, Vojtěch ; Vampola, T.
Velopharyngeal insufficiency is modeled in frequency domain by the transfer matrix method in connection with conical acoustical elements. The vocal tract is considered as a branched system with two nasal ducts. The influence of viscous losses and radiation impedance both at the level of the lips and at the level of the nostrils are considered. Configuration of the vocal tract corresponds to the vowel /a:/. The modal analysis is performed and the results are compared with those gained from 3D FEM models.
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PROBLEMS OF SINGER’S FORMANT MATHEMATICAL MODELING
Radolf, Vojtěch
Theme of the paper belongs into the field of acoustics in biomechanics. In co-operation with foniatric departments in Czech Republic the spatial and then simplified geometric models of acoustic human vocal cavities were created. Using various mathematical models the dynamic characteristics of the models were finding out. One of the objectives of the project is to investigate singer's formant cluster. The mathematical models are designed to find such configuration of acoustic cavities, respecting real physiological limits, which leads to excitation of predefined acoustic resonances. It is so called formant tuning. Using these models the appropriate geometry for the singer's formant cluster formation were searching for.
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Optimization of resonance properties of the human vocal tract by variation of cross-section and length of acoustic elements
Radolf, Vojtěch
Theme of the paper is focused on optimization possibilities of geometrical form of human vocal tract. An optimization process is designed to find such configuration of acoustic cavities, respecting real physiological limits, which leads to excitation of predefined acoustic resonance. Especially frequency domain between the third and the fifth formant is important for voice timbre, namely for singing voice ('the singer's formant'). Two various 1D optimization methods, computing time and accuracy of solution are compared. The first method is a general procedure of numerical searching for the minimum of objection function, the second is an energetic iterative procedure using non-dimensional sensitivity functions. Both length and cross-section area of conic elements are varied.
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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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Acoustic modal analysis of male vocal tract for Czech vowels
Dedouch, K. ; Horáček, Jaromír ; Vampola, T. ; Švec, J. G. ; Kršek, P. ; Havlík, R.
Acoustic frequency-modal characteristics of six finite element models of a male vocal tract are presented and analysed. The FE models correspond to the vocal tract geometries for the Czech vowels /a/, /e/, /i/, /o/, /u/ and /y/ were obtained using the magnetic resonance imaging technique. The computed results of the acoustaic modal analysis are in a reasonable agreement with the data on formants known form the Czech phonetic literature.
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Measurement of acoustic pressure in supraglottal spaces
Vokřál, J. ; Vohradník, M. ; Horáček, Jaromír
The aim is the measurement of acoustic pressure in supraglottal acoustic spaces by miniature microphones. The microphone was placed at the end of laryngeal wire applicator and its position was changed continually from the mouth to the vocal folds. This sources of acoustic signal were used: the own voice - vowels ´A´ and ´E´, and the electronic laryns. Natural frequencies nad acoustic mode shapes of the air vibration were investigated.
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