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Visualization of sound fields
Kovář, Petr ; Klusáček, Stanislav (referee) ; Havránek, Zdeněk (advisor)
This bachelor's thesis deals with problems of acoustical field visualization using near-field acoustical holography. This method is often refered as NAH. Within the thesis the basic acoustical field variables are processed and described. Two algorithms were analysed, namely the Statistically Optimal Algorithm (SONAH) and the Iterative Algorithm using the Fourier Transform (STFT) with a K-filter (Wave-Domain Filter). These algorithms are described in detail. The outcome of the practical part of this thesis is the application for sound pressure visualization. The application is created in the LabVIEW environment from the known codes and the calculation of the sound pressure is performed with one of the two algorithms described in this thesis. From depicted acoustical maps the disadvantages of this method and differences between algorithm are shown. These algorithms are then compared according to speed of the calculation.
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Methods for detecting acoustic sources using microphone arrays
Durkoš, Michal ; Rampl, Ivan (referee) ; Míča, Ivan (advisor)
his paper denotes various possibilities of localization of sources of acoustic signals. It informs the reader about possibilities of using beamforming and it´s basic conditions and rules. In detail it denotes delay-and-sum beamforming, which can be used for both localization of signal sources and for improving the signal by extending signal-to-noise ratio. In the last part of this paper process of simulation of incidence of sound signal on the microphone array is shown, experimental measures are noted and so is their evaluation.
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Localization acoustic near-field sources
Šuránek, David ; Sysel, Petr (referee) ; Míča, Ivan (advisor)
This thesis is focused on acoustic source localization in near field situation. First part of this thesis is dedicated to examining the fundamental issues of acoustic source localization. After that are some of acoustic source localization methods described. Next part is focused on implementation, verification of functionality, comparing of the successfulness and results of the localization. In conclusion are summarized the outcomes of the thesis.
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Statical acoustical sources localization
Mikeš, Petr ; Holešinský, Pavel (referee) ; Míča, Ivan (advisor)
The microphone array can be used in many important applications. The primary usage, which most of other applications are based on, is only: acoustic sources localization and separation of each signal from their compound. The microphone array is usually included in ordinary mobile phones, where it reduces noise and sound of its surrounding that otherwise degrades vocal speech. Other microphone array utilization is in for example speech identification, speakers’ localization or signal isolation of one speaker.
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Microphone arrays for beamforming
Grénar, Milan ; Smékal, Zdeněk (referee) ; Míča, Ivan (advisor)
The aim of the bachelor's thesis is to assemble theoretical and practical information about methods for estimate direction of arrival whereas there is an emphasis on beamforming. There are introduced general conventions which are being used to measure with multichannel microphone array. Part of this thesis is the implementation of the DAS beamformer in several modifications, including verification of the functionality in ideal and real conditions.
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Microphone array application
Toman, Vít ; Hanák, Pavel (referee) ; Fedra, Zbyněk (advisor)
Master’s thesis deals with description of issues of reading spatial audio signals using microphone array. Basic method of beamforming (Delay and Sum) is characterized on basis of chosen conception of the microphone array. Specific issues of audio detection and digital signal processing of converted audio signals are characterized and some ways how to solve the issues are adumbrated. Features and limitations of chosen ARM processor in the digital processing of multiple audio signals are described. Especially features and limitations of an internal A/D converter from the perspective of the beamforming are described.
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Beamforming system with FPGA
Vadinský, Václav ; Vágner, Martin (referee) ; Havránek, Zdeněk (advisor)
This thesis deals with processing signals from the microphone arrays for sound source localization. Compares different types of fields, such as cross-field and circular array. It is shown here how to implement Beamforming on FPGA and design of signal processing with a microphone array.
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Beamforming using microphone arrays
Bartoň, Zdeněk ; Schimmel, Jiří (referee) ; Míča, Ivan (advisor)
The aim of the master thesis is to sum up theoretical information about beamforming methods of microphone arrays and to verify their functionality. At the beginning of this work there are simulated different varietes of linear uniform and nonuniform microphone arrays and circular arrays. The results are verificated by a practical measurement in ideal conditions. Then I will focuse on implementation of the DAS(Delay And Sum), SAB(Sub Array Beamforming), CDB(Constant Directivity Beamforming), CDB-CA(CDB-Circular Arrays) beamformer including theoretical and practical verification of the functionality in ideal conditions. At the end of this thesis are all beamforming methods compared with each other at SNR(signal to Noise Ratio) and directivity parameters.
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Acoustic Holography
Vacula, Jan ; Janoušek, Michal (referee) ; Prokop, Aleš (advisor)
This bachelor´s thesis is focused on description and process during contactless identification of sound source for near and far field. Principles of individual methods of acoustic holography are relatively shortly described and for details of this problem (on the level of algorithm of software equipment) you can see the references below thesis, which were the basic theory of my study. The introduction was conceived like description of “acoustics world”. You can find the basic information and principles about sound propagation in space and their mathematical contain at time. For this it was essential to define quantity and their units. Subsequently there is inventory of used sensors and their own construction for this measurement. Next chapter point to some techniques of acoustic holography used in practice. It includes mainly a method NAH (Nearfield Acoustical Holography) and SONAH (Statistically Optimised Nearfield Acoustical Holography) used for near-field. For reconstruction of far-field is shown principle of a method of Beamforming and manual measurement by intensity probe. The ending is focused on a concrete application these methods on combustion engines of cars.
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