National Repository of Grey Literature 211 records found  beginprevious202 - 211  jump to record: Search took 0.01 seconds. 
Simulace lidského hlasu s využitím MKP modelu vokálního traktu
Horáček, Jaromír ; Griffond-Boitier, F.
Finite element models of male vocal tract for Czech vowel /a/ are analyzed and used for numerical simulation of phonation. The models were designed from the MRI the subject during phonation. The acoustic signals for the vowel /a/ are simulated using the transient analysis. For excitation of the supraglottal spaces the intraglottal pressure or airflow rate generated by the aeroelastic model of vocal folds self-oscillations is used. The frequency and time response functions calculated near the lips and in front of the mouth are compared with acoustic measurements.
Dynamic characteristics of the human vocal tract influenced by the cleft palate
Vampola, T. ; Horáček, Jaromír ; Bauma, V.
Finite element models of supraglottal tract for Czech vowels /a/ and /u/ are analyzed considering the cleft palate. Performed acoustic modal analysis is focused on investigation of the influence of the area of cleft palate on the formant frequencies F1-F3. The results for the vowel /a/ indicate, that after a small jump of the acoustic natural frequencies for a very small cleft the frequencies F1 and F2 are influence by increasing size the cleft only very slightly. The influence of the cleft on the phonation of the vowel /u/ is considerable higher.
3-D FE model of the human vocal folds for dynamic computations
Vampola, T. ; Horáček, Jaromír
The article describes the design of a 3D finite element (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. The model is determined mainly for studies of dynamical stresses in the vocal fold tissue during vocal folds collisions.
Numerical modelling of effect of tonsilectomy on production of Czech vowels /a/ and /i/ based on FE model of human vocal tract
Švancara, Pavel ; Horáček, Jaromír
Finite element models of the human vocal tract for the Czech vowels /a/ and /i/ were modified by adding acoustic spaces that occurs after tonsilectomy. The resonant characteristics of the models were studied and then the pronunciation of the vowels was simulated. The results show that tonsilectomy causes frequency shift of 3rd (~180 Hz) and 4th (~120 Hz) formants to lower frequencies for vowel /a/ and frequency shift down of 2nd, 4th and 5th formant for vowel /i/ (all ~100 Hz).
Dynamic properties of some physical models of artificial vocal folds
Šidlof, Petr ; Veselý, Jan ; Horáček, Jaromír
The paper presents results of measurements of acoustic and vibratory characteristics of several artificial vocal fold prototypes based on various principles. During measurements the dynamic subglottal pressure and output acoustic pressure were recorded. Spectral analysis of the signals was performed, and where the construction permitted, the vibrations were also observed by means of videostroboscopy. In some cases, a computer-modelling-based shape and material optimizations is possible with the aid of the mathematical models developed in IT AS CR.
Numerické řešení proudění kolem vibrujícího leteckého profilu
Honzátko, R. ; Horáček, Jaromír ; Kozel, K.
The work deals with numerical solution of 2D inviscid and viscous incompressible flow over the airfoil NACA 0012 in a channel. The finite volume method with cell-centered schemes at quadrilateral C-mesh is used. Governing equations are the Euler equations in the case of inviscid flow and Navier-Stokes equations in the case of viscous flow. The small disturbance theory applied to a numerical solution of unsteady flow is mentioned and the brief introduction is also given to the ALE method.
Fyziologické údaje získané z aeroelastického modelu kmitání lidských hlasivek
Horáček, Jaromír ; Laukkanen, A. M. ; Šidlof, Petr
The results of the numerical simulations show that the aeroelastic model for vocal fold self-oscillations corresponds well with the existing clinical data and it thus gives the possibility to study independently various phonation related variables that may in living subjects be obscured by the co-existence of many variables. Furthermore, the model of course naturally gives the possibility to study also such variables that are impossible to study in living subjects.
Počítačová simulace lidského hlasu s využitím aeroelastického modelu hlasivek a MKP modelu vokálního traktu člověka
Horáček, Jaromír ; Šidlof, Petr ; Švec, J. G. ; Griffond-Boitier, F.
The developed finite element (FE) model of real male vocal tract that corresponds to the Czech vowel /a/ is used for numerical simulation of phonation. The FE model was designed from the magnetic resonance images (MRI) of the subject during phonation. The acoustic signals for the vowel /a/ are simulated using the transient analysis of the FE model in time domain. For excitation of the acoustic supraglottal spaces the intraglottal pressure generated by the aeroelastic model of vocal folds self-oscillations is used. The frequency and time response functions are calculated in front of the mouth.
Konečnoprvkové modelování akustiky mužského vokálního traktu s uvážením rozštěpu patra
Dedouch, K. ; Horáček, Jaromír ; Vampola, T. ; Vokřál, J.
Finite element (FE) models of real male vocal and nasal tract corresponding to the Czech vowels / i / and / u / are analyzed in this paper. The FE models were designed by direct transferring data obtained from MRI images. The acoustic signals for the Czech vowels / i / and / u / are simulated using transient analysis. The frequency and time response functions are calculated in the FE nodes near the lips, nostrils and at the vocal folds.
Experimentální akustická modální analýza modelu mužského vokálního traktu
Horáček, Jaromír ; Veselý, Jan ; Pešek, Luděk ; Růžička, P.
Acoustic properties of a physical model of real male vocal tract corresponding to the Czech vowel / a / are analyzed by the experimental modal analysis. The model was obtained from the magnetic resonance images (MRI), taken during the subject phonation by the method of rapid prototyping. The random excitation was applied at the vocal folds and the response was measured along the vocal tract. The frequency response functions were evaluated by a global identification method. The resulting eigenfrequencies (formants) and the acoustic mode shapes of vibration are compared with the acoustic measurements carried out during the MRI realization.

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