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Spectral analyse of sound in space acoustics
Port, Martin ; Bereznanin, Martin (referee) ; Rozman, Jiří (advisor)
This thesis is an introduction to the problems of acoustics and is focused on the variables describing the noise. The methodology for measuring noise in relation with valid hygiene standards is analyzed in next section. The noise levels at work required by government regulation no. 148/2006 are summarized in a subsequent charter. The next section is an introduction to the analyzer PULSE 3560B from Brüel & Kjar. This work describes a software called Labshop, which is designed to analyze noise and vibrations. It also describes the most common features Acoustilyzer NTI AL1. The practical part was to measure the reverberation, noise, frequency spectrum and plott the distribution of noise with noise maps of various auditoriums.
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Pure tone audiometry
Maršálková, Leona ; Harabiš, Vratislav (referee) ; Chmelař, Milan (advisor)
The presented master’s thesis deals with the acoustics, specifically with the selected characteristics of the sound. It focuses on the anatomy of the auditory system and its function. The work describes the testing approaches for an evaluation of the auditory organ function and introduces modern methods used for the hearing tests, especially pure tone audiometry. A part of the thesis is dedicated to a concept of an audiometer for pure tone audiometry, which is presented in a detailed block diagram along with a description of its working components. Included chapters describe the partial circuits of the audiometer supplemented by the calcuations of its individual elements. The concluding part of the thesis deals with the evaluation of the device’s functionality.
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Acoustical simulation of going car
Lacko, Tomáš ; Horka, Michal (referee) ; Sigmund, Milan (advisor)
This project includes an overview of different processing methods phonograms. It focuses primarily on time - frequency analysis carried out using Fast Fourier Transform (STFT). The main essence is to evaluate the time - frequency analysis of recorded motor vehicle, driving at different options, together with an analysis of driver activity in these variants. Based on the results of the analysis deals with the creation of synthetic audio signals of motor vehicle records. Further addresses the creation of the program for acoustic simulation engine is running smoothly when driving a car. Processing recorded signals and their evaluation is transferred using Matlab 7.7.0 ( R2008 )
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Psychoacoustical Measurement of Binaural Hearing Characteristics
Novotný, Ota ; Trzos, Michal (referee) ; Schimmel, Jiří (advisor)
This diploma thesis deals with a binaural hearing issues (it means hearing by both of ears), a human hearing ability to locate position of a sound source at three-dimensional space and parameters that affect this ability. In the second part, it focuses on psychoacoustic experiment, its main features and errors that can occur and which affect a results credibility. Method of pair comparisons is described more closely here. The last part of this thesis describes a technical solution of experiment in Java environment. The application should have a graphical interface and should be able to register a new user and perform a psychoacoustical experiment. The process of experiment is following. The aplication selects a random position of defined virtual sound source on the defined range and it plays this sound into headphones on button click. The users task is to set the application controls, representing a virtual sound source position, that way, where the user hear the sound come from. On another button click the application plays the same sound, but this sound comes from application controls set position (set by user). User compares this pair of sounds and modifies the position of second sound source until these two positions are same. The application stores these results for later processing on another button click. Principles of generating testing sound sources (sine wave, narrowband noise and sound file with wav extension) and their 3D positioning by measured head model impulse responses correlation are described thereinafter. An ability of human hearing system to locate a virtual sound source in dependence on sound parameters is discussed in conclusion.
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Preparation of nanoforms of layered piezoelectric of systems BI2O3-TA(2)O(5)-AO (A=CA,SR,BA)
Štarman, S. ; Matz, V. ; Kváča, Z. ; Mohyla, M. ; Olšák, V. ; Plocek, Jiří ; Vaněk, Přemysl ; Tylš, B.
Based on the known Aurivillius phases types ABi2Ta2O9 and A2BiTaO6 ( A=Ca, Sr, Ba) were supplemented with new compositions of layered tantalates, which resulted the possibility of the existence of a new phase Sr2BiTaO6. Ternary compounds with piezoelectric structure were prepared as nanoforms by solgel reactions of homogeneous acetate Bi, Ta, A and subsequent annealing in a controlled atmosphere. Annealing temperature was determined from DSC curves based on the weight loss and phase transitions. Composition and structure of nanocrystals has been analyzed by X-ray diffraction (XRD), scanning nanomorphology (SEM) and acoustic measurements.
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Computer modeling of effects of vocal exercising with a tube on vocal tract sound power transfer
Horáček, Jaromír ; Vampola, T. ; Laukkanen, A. M. ; Švec, J. G.
Two 3D finite element (FE) models were constructed, based on CT measurements of a subject phonating on [a:] before and after phonation into a tube. Acoustic analysis was performed exciting the models by acoustic flow velocity at the vocal folds. The generated acoustic pressure of the response was computed in front of the mouth and inside the vocal tract for both FE models. Average amplitudes of the pressure oscillations inside the vocal tract and in front of the mouth were compared to display a cost-efficiency of sound energy transfer at different formant frequencies. Comparison of the pressure oscillation inside and outside the vocal tract showed that formants differ in their efficiency, F4 (at about 3.5 kHz, i.e. at the speaker’s or singer’s formant region) being the most effective. The results suggest that exercising on semi-occlusions help in improving the vocal economy.
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Notes on wave and waveguide concepts in AE
Převorovský, Zdeněk
A purpose of this paper is to point out some current problems related with wave concepts and quantitative AE source identification. Main tasks concerning AE detection, localization and source identification are discussed and their advances during the last ten years are mentioned.
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