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Multi-channel Methods of Speech Enhancement
Zitka, Adam ; Balík, Miroslav (referee) ; Smékal, Zdeněk (advisor)
This thesis deals with multi-channel methods of speech enhancement. Multichannel methods of speech enhancement use a few microphones for recording signals. From mixtures of signals, for example, individual speakers can be separated, noise should be reduced etc. with using neural networks. The task of separating speakers is known as a cocktail-party effect. The main method of solving this problem is called independent component analysis. At first there are described its theoretical foundation and presented conditions and requirements for its application. Methods of ICA try to separate the mixtures with help of searching the minimal gaussian properties of signals. For the analysis of independent components are used different mathematical properties of signals such as kurtosis and entropy. Signals, which were mixed artificially on a computer, can be relatively well separated using, for example, FastICA algorithm or ICA gradient ascent. However, difficult is situation, if we want to separate the signals created in the real recording enviroment, because the separation of speech people speaking at the same time in the real environment affects other various factors such as acoustic properties of the room, noise, delays, reflections from the walls, the position or the type of microphones, etc. Work presents aproach of independent component analysis in the frequency domain, which can successfully separate also recordings made in the real environment.
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Administration of development documetation over WWW I
Kolář, Miroslav ; Sysel, Petr (referee) ; Balík, Miroslav (advisor)
Master`s thesis is based on the assignment of company Honeywell to create integral system for saving and management of development documentation. Designed system will introduce data warehouse with transparent display of documents being connected with development of customer’s requirements, products and tests, test runs. Solution consists of two parts: A – Requirements and Products and B – Tests, Test runs and Person, whereas Master`s thesis deals with the part B. For system creation utilities of following programming languages were used HTML, PHP, JavaScript and database system MySQL. In the first phase was designed database structure (tables and relations between them). Except that was designed structure for authorization algorithm and integral concept of whole application was created. The second phase is realization. At first are created supporting algorithms. It is servicing database by functions, uniform displaying results from database and authorized access of users to the application. Further data library for integral display data forms, based on used template system Smarty and other libraries, f.e. attribution of the files to records in SQL tables. Important part was implementation of designed database system and related programs. In Tests and Test runs there is user interface established and individual relations between them. According to assignment all fundamental programs were designed together with support instruments. Individual source files are saved in transparent structure of folders, so this structure is possible to apply on any computer, where are installed programs to web hosting. The result of Master`s thesis is then integrated progress report together with functional source codes.
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Acoustical analysis of mechanical watsches
Dohnal, Marek ; Balík, Miroslav (referee) ; Sigmund, Milan (advisor)
This thesis is focused on the analysis of the characteristics of mechanical watches on the basis of their sound. There are theoretically analysed usual mechanical defects and disorders of watches and compensation of those defects. Particular attention is given to disorders, that can be extracted from the recorded acoustic sound of watches. There are also solved most appropriate methods of recording with a respect to the minimisation of ambient acoustic interference. The main part of this work is experimental measurement on watches and evaluation of achieved acoustic data. For this purpose, an autonomously running software were developed.
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Precision audio preamplifier for headset measurement
Šimek, Michal ; Balík, Miroslav (referee) ; Hanák, Pavel (advisor)
This thesis deals with microphone and headphone preamplifier for microtelephone and headset. The design shall meet the electrical interface requirements set out in ITU-T Rec. P.381(08/2012). The design includes a voltage converter, microtelephone bias and both a battery and an external power supply. In this work is also described the design of printed circuit board and the solution of a low noise in the whole circuit. The aim of this thesis is to design, built and embed the laboratory fixture into a metal box. Finally, measure the product on an APx525 audio precision analyzer.
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Near-field measurement of a modular subwoofer unit
Borodáč, Samuel ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
The bachleor thesis describes influence of the type of loudspeaker baffle and methods of measuring the subwoofer unit on the frequency response at low frequencies. The work describes the configuration of measurements and the procedure in the analysis software APx500, as well as the export and evaluation of measured values. Moreover, the thesis also includes the results of measurements, its brief analysis and observation of phenomena affecting the measurement of the modular frequency response of the loudspeaker unit in the near field, as well as achieving the overall resulting frequency response of the loudspeaker unit.
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Design and Construction of Transmission Line Loudspeaker Cabinet
Dobiášovský, Jiří ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
Thesis is dealing with the topic of design and construction of the transmission line loudspeaker enclosures. Theoretical part is focused on speaker choice, its design elements and their influence on parameters of the speaker. Individual parameters of the speaker, mathematical equations for their determination and choice of suitable speaker for transmission line loudspeaker enclosure is furthermore discussed and defined. Principle of transmission line enclosures is discussed together with its advantages and disadvantages compared to other types of enclosures. The individual design elements and their influence on the resulting characteristics of the enclosure are described. In the practical part, with regard to the facts stated in the theoretical part of the work, a suitable speaker is selected and the subsequent design and construction of a variable transmission line speaker is described. This might serve as a teaching aid in future. Part of the work is also a description of procedures for measuring loudspeakers with multiple speakers or resonators.
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2x400W/8 ohms end amplifier
Káňa, Lukáš ; Balík, Miroslav (referee) ; Káňa, Ladislav (advisor)
Submitted text deals with a power amplifier intended for usage in music electronics. First part is related to the common problems of low-frequency amplifiers including principles and individual circuit wiring types. Next part is related to description of self-made power amplifier including wiring scheme diagram. The end of the text concerns about mechanical construction of mounting box and design of possible module layout inside a device.
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Implementation of time-variant convolution processor
Brhel, Tomáš ; Vrba, Kamil (referee) ; Balík, Miroslav (advisor)
In this thesis there is a design of universal time-variant convolution FIR processor. Proposed algorithm is ready to process long signals with reduced process delay. Furthermore, there are proposed methods for smooth crossfade between different impulse responses. Algorithm is implemented in Matlab environment and later as a VST plugin.
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Subjective and Objective Assessment of Speech Quality
Bezdíček, Martin ; Balík, Miroslav (referee) ; Vondra, Martin (advisor)
This Bachelor's thesis is focused on subjective and objective methods for evaluation of speech quality. In the first part, the quality of transmitted speech signal and its distorting effects are given. Futher, subjective and objective methods for evaluation of speech are described. The objective methods: Signal to Noise Ratio (SNR), Segmental Signal to Noise Ratio (SSNR), the methods for evaluation in spectral area (Log Likelihood Ratio Measures and Cepstral Distance) and also Perceptual Evaluation of Speech Quality (PESQ). The next part deals with the correlation analysis which is used for the comparison of subjective and objective methods. In the last part of the bachelor thesis the results of subjective and objective methods are presented. Finally on the basis of correlation analysis with the results of subjective method, the best objective method is recommended.
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