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The spectral and directional analysis of xylophone, vibraphone and glockenspiel
Hoffman, Pavel ; Indrák, Michal (referee) ; Jirásek, Ondřej (advisor)
Bacherlor‘s thesis deals with spectral analysis and directional characteristics of idiophonic instruments, xylophone, vibraphone and glockenspiel. It analyzes various details during spectral analysis, that could have an effect on the spectrum of a given instrument, and especially on its inharmonicity, thus analyzing its effect on the hardness of mallet, dynamics and the location of the mallet striking the bars (stones, wooden plates). It examines the changes in the harmonic range and the formant areas of instruments. The thesis further describes the mallets, the instruments themselves, theoretical base and the means by which the sound samples were acquired and processed.
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Loudspeaker Box with Variable Crossover Frequency
Tomášek, Martin ; Balík, Miroslav (referee) ; Schimmel, Jiří (advisor)
This bachelor´s thesis deals with middle-sized loudspeaker system in D´Appolito configuration. The aim of this thesis is to design and to realize the loudspeaker system, which includes selection of suitable loudspeakers and their position in designed baffle including design of variable crossover frequency. The text is divided into a few sections, where are the points of this project described. In the first half there are briefly described basic principles of loudspeakers and design loudspeaker systems, especially 2-way loudspeakers, and specific properties of D´Appolito configuration. Then there are described principles of frequency crossovers used in loudspeaker systems and what is expected for their construction. In the second half, there is described realization of baffle itself and variable frequency crossover. Because this thesis concurs to semestral thesis, there is also a chapter about simulation. In the end there are diagrammatized the measured data of frequency and dispersion characteristics and a few dispersion characteristics for different crossing frequences.
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The comparison of acoustic properties of guitars from the same product line
Trávníčková, Hana ; Indrák, Michal (referee) ; Jirásek, Ondřej (advisor)
This work is dealing with acoustic features of Furch guitars. In theoretical introduction is possible to find an information about basic characteristics of a tone. Following chapter about acoustic guitars is dealing even with mostly used types of woods for their manufacturing. In special chapter are described spectres of signals, LPC analysis, sound radiation of instruments and Chladni figures. Mentioned terms have been evaluated from measurements and are available in practical part of this work also including description of implementation of the measurement. As an output of this work is a comparison of acoustic features of measured guitars, their colours and modes.
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Indirect vibration analysis using a mobile phone microphone
Plodková, Zuzana ; Huzlík, Rostislav (referee) ; Zuth, Daniel (advisor)
The bachelor thesis deals with the possibility of using a recorded signal from a mobile phone for vibration analysis. The first half of the thesis is a research generally dedicated to microphones, microphones in mobile phones and technical diagnostics. The chapter about microphones discusses the principle of their operation, further it analyzes the most important technical parameters and finally divides microphones according to their construction. In case of microphones in mobile phones there is mentioned the most commonly used type of microphone and its structure including a description of possible sound filtration. Possible ways and approaches to processing the measured signal are mention in the chapter abou technical diagnostics. The second part of the thesis is devoted to repeated measurement and subsequent processing of measured values. An evaluation of efficiency of the method of measuring the signal with a mobile phone for vibration analysis by comparison with the results obtained by a professional measuring technique follows.
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Possibilities of noise measurement on machine tools and determine their source
Malušek, Pavel ; Šubrt, Kamil (referee) ; Kroupa, Jiří (advisor)
This bachelor’s thesis deals with methods for sound source localization. It also analyzes types of microphones which are used for this purpose. There are detailed described the parameters of the microphones at first, principles of every method and their application in practice then. The aim of this thesis is application of these methods in determining the sound sources on machine tools and evaluation the advantages of individual methods for the specific purpose.
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Loudspeaker System for Reproduction of Low Frequencies with Directional Radiation
Skvaril, Šimon ; Husník, Libor (referee) ; Schimmel, Jiří (advisor)
Final product of this work is design of speaker baffle which will have directional radiation at low frequencies. In the course of the work, propagation of sound waves and their beaviour at obstacles are described. The computational method FDTD and the K-wave toolkit for MATLAB, which uses this method, are described. In MATLAB a virtual model of speaker baffle is created and proposed solution is verified. Next step is creation of scaled model of speaker baffle on which agreement of theoretical computations with real-world measurment is verified. Final step is creation of prototype of speaker baffle,, whose parameters are measured, including polar response.
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Computing directivity patterns in Comsol Multiphysics
Ryšánek, Martin ; Lukeš, Zbyněk (referee) ; Raida, Zbyněk (advisor)
The individual project – Computing directivity patterns in Comsol Multiphysics. In the first part, the theoretical background for monopole antennas is reviewed. The second part is focused on the analysis of several types of monopoles in COMSOL Multiphysics, and on the calculation of their radiation patterns and impedances. Finally, simulation results are presented and discussed.
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Influence of drivers position on the characteristics of the loudspeaker system
Bičan, Jan ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
This thesis deals with the measurement and description of properties of the two-way variable modular loudspeaker system marked as OM-3, especially the influence of the mutual position of drivers on its characteristics. The thesis examines individual factors taking their contribution on characteristics of the loudspeaker system in total. Further it measures and evaluates options of compensations of mutual position changes of drivers using an all-pass filter. Within this thesis is also included laboratory task preparation which is focused on this problematics.
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