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Experimental investigation of air pressure and acoustic characteristics of human voice. Part 1: Measurement in vivo
Horáček, Jaromír ; Radolf, Vojtěch ; Bula, Vítězslav ; Veselý, Jan ; Laukkanen, A. M.
This contribution is aimed to provide material that can be used to develop more realistic physical models of voice production. The experimental methodology and the results of measurement of subglottal, oral (substitute for subglottic) and acoustic air pressure (captured at a distance of 20 cm in front of the subject’s mouth) are presented. The data were measured during ordinary speech production and when the acoustic impedance and mean supraglottal resistance were raised by phonating into differently sized tubes in the air and having the other end submerged under water. The results presented in time and frequency domain show the physiological ranges and limits of the measured pressures in humans for normal and extreme phonation.
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Influence of geometric configurations of the human vocal tract on the voice production
Vampola, T. ; Horáček, Jaromír
The three-dimensional (3D) finite element (FE) model of the human vocal tract was constructed, based on CT measurements of a subject phonating on [a:]. A special attention is given to the higher frequency range (above 3.5 Hz) where transversal modes exist between piriform sinuses (PS) and valleculae (VA) and where the higher formants can create a formant cluster known as the speaker’s or singer’s formant. Since the human ear is most sensitive to frequencies between 2 and 4 kHz concentration of sound energy in this frequency region (F4-F5) is effective for communication.
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Computer simulation of musical singer’s voice based on MRI and acoustic measurement
Radolf, Vojtěch ; Nissinen, A. ; Laukkanen, A. M. ; Havlík, R. ; Horáček, Jaromír
An inverse method was used to estimate the vocal tract geometry as a 1D model on the basis of acoustical characteristics of a professional musical singer before and after vocal exercising. The basic geometrical data for the model were obtained from MRI registered during sustained phonation of vowels [a:], [i:], [u:] produced in naive and professional ways. The model was used for numerical simulations of the voice signals. The results of simulation were compared to the acoustic recordings. According to the results, a singer’s formant cluster was accomplished after exercising. It seemed to be due to lowering of the larynx and lengthening and narrowing of the epilarynx. There was a qualitative agreement between 3D measurements of MRI and the results of modeling. The results suggest that for a singer’s formant cluster a relatively low pharynx over epilarynx ratio may be sufficient, at least if the larynx lowers.
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The self-excited vibration of the NACA0015 profile
Vlček, Václav ; Zolotarev, Igor ; Kozánek, Jan
The two-dimensional flow patterns around the profile NACA0015 vibrating in self-excitation modes were measured in the wind tunnel by optical methods. The Mach numbers for the self-excited vibrations were in the interval 0.2 – 0.45. Results of the interferometric measurement and the profile kinematic movements during the self-oscillations are presented.
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Collision of a rotating spherical particle with flat wall in liquid
Lukerchenko, Nikolay ; Kvurt, Y. ; Chára, Zdeněk ; Vlasák, Pavel
The collision of the rotating spherical particle with a flat wall in liquid was studied experimentally. The glass and steel beads rotating in water and silicon oil were used. A high-speed video system recorded the bead motion before and after the collision. It was shown that the restitution coefficient depends not only on the Stokes number but also on the particle angular velocity; the restitution coefficient decreases with increasing of the rotational Reynolds number and decreasing of the Stokes number. These results can be useful in modelling of the two-phase flows near solid boundaries.
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Dependence of saltation parameters on bed roughness and bed porosity
Kharlamova, Irina ; Vlasák, Pavel
In numerical models of bed load transport a bed structure of channel could be described by two parameters, a size of bed particles and a standard deviation of normal distribution of bed particles in the vertical direction. The present paper deals with the effect of bed parameters on average length and height of one jump of saltating particle. A new formula was proposed for bed roughness based on size and standard deviation of the normal distribution of the bed particles. The dependences of length and height of the jump on the diameter of the saltating and bed particles were determined for different variation of vertical distribution of the bed particles.
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Motion of rotating spherical particles touching a wall
Chára, Zdeněk ; Vlasák, Pavel ; Keita, Ibrahima
The paper deals with an analysis of motion of rotating spherical particle in calm water, when the particle is in contact with a smooth, horizontal wall. The motion was visualized by a fast digital camera at 1000 frames/second. Based on software analysis the particle trajectories as well as rotational velocities were determined. Values of vertical, horizontal and rotational velocities were used as input parameters for numerical model and the results are compared with experimental data. Experiments were performed with glass particle of diameter 25 mm, initial values of rotational speeds varied from 500 to 3000 revolution per minute.
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Investigations of orthotropic decks
Urushadze, Shota ; Frýba, Ladislav ; Pirner, Miroš
The investgations of orthotropic decks carried out in the Institute of Theoretivcal and Applied Mechanics,v.v.i., Academy of Sciensces of the Czech Republic, for the project of the European Union „BRIFAG“ are described. The response of orthotropic decks is studie under dynamic loads including the crack propagation, estimation of fatigue life of the bridge elements, e.t.c. It was found that the most vulenrable detail appeared at the spatial connection of the deck with cross and longitudinal beams. The most important results are shown in a a figure of stress ranges as a function of the number of stress cycles.
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