National Repository of Grey Literature 156 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
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.
Software Sound Level Meter
Menšík, Václav ; Sysel, Petr (referee) ; Schimmel, Jiří (advisor)
This thesis discusses noise measurement devices, design and implementation of a software sound pressure meter. Sound pressure meter requirements specified by the IEC 61672 standard and selected acoustic physical properties are discussed. Further, the JUCE framework is presented along with an of the graphical user interface and digital signal processing capabilities of the SoundMeter program.
Audio codecs and their perceptual quality evaluation
Hudec, Andrej ; Schimmel, Jiří (referee) ; Rajmic, Pavel (advisor)
The bachelor thesis deals with audio codecs and tests to evaluate their listening quality. The thesis offers a description of the properties of human hearing, a brief introduction to the issues of audio coding, types of audio data compression and listening tests. The bachelor thesis also contains a theoretical description of the coding processes of selected audio codecs, evaluation of measuring their computational complexity and evaluation of listening quality of each of them using listening tests. HTML, CSS, Javascript and Python programming languages were used to implement the listening test environment. The audio files examined in the listening tests were obtained using the FFmpeg library.
Compensation of Loudspeaker Frequency Response for a Wider Listening Area
Beránek, Šimon ; Říha, Kamil (referee) ; Schimmel, Jiří (advisor)
This bachelor thesis studies problematics of calculating average impulse responses of rooms. Measuring signals like MLS or linear/exponential sine sweep are described. Basic methods of interpolation are explained and their applicability in frequency response calculations is described. Digital filters are explained as a tool for frequency response equalization. First part of this thesis tests methods of interpolation on 64 measured impulse responses. These methods have been further optimized and one was chosen to calculate the average impulse response for each of the measured rooms. Second part consists of AB*X listening tests deployed to find subjective aural differences of the interpolated impulse responses and few of the measured impulse responses. These interpolated impulses responses were further compensated using a warped filter library.
Simulation of Audio Signal Distortion in Perceptual Audio Encoder
Peloušek, Tomáš ; Rajmic, Pavel (referee) ; Schimmel, Jiří (advisor)
This thesis deals with the issue of the creation of a programme that would simulate the distortion that appears during the process of lossy audio coding. As the environment for the creation, the MATLAB programming language has been chosen. An encoder, which changes the subjective signal quality according to customer preferences for the bitrate, has been created as a practical part of this thesis. Its function is based on a dynamic bit allocation technique and includes an optional window switching algorithm. The theoretical background for the creation of the programme consists of an explanation of the main principles of lossy coding with emphasis on MPEG1 layer 3 operating principles. The practical chapter describes how the created programme and its parts work, and it includes results of the run quality testing. The testing was conducted using the objective assessment method PEMO-Q, and consisted of comparing the objective quality of the programme’s outputs to the quality of samples on which a regular MP3 encoder with identical settings was used.
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.
Design and Realization of Acoustic Treatment of Small Recording Studio
Tkadlec, Vojtěch ; Husník, Libor (referee) ; Schimmel, Jiří (advisor)
This bachelor thesis deals with the topic of acoustic properties of an enclosed space, their detection and modification. The thesis examines the acoustic properties of a small enclosed space, which were determined by simulation using a virtual 3D model and subsequently verified by measurement. After finding out the properties, a substantial part was also devoted to their modification, where the task was to design the acoustic elements so that the resulting length of the reverberation time corresponds to the optimal values for a small recording studio. The design of the elements is followed by their construction, followed by a re-measurement of the space. Furthermore, the work summarizes the principles of modeling and simulation of 3D models.
Automation of Audio Device Measurement on APx500 Platform
Panáček, Richard ; Sysel, Petr (referee) ; Schimmel, Jiří (advisor)
This bachelor thesis is focused on the options of measurement automatization on the platform APx500. This automatization should be achieved not only with the use of the measuring program APx500, but also with the use of third-party programs. In these programs, measuring projects should be created. Among many compatible programs, there are LabVIEW, VEE, and a programing environment using Visual Basic language. The thesis is divided into many parts. The first part is focused on the introduction of the APx500 program and its functions. The second part is aimed at the connecting program APx500 with third-party programs using APx API. The practical part of this thesis is about the creation of a measuring project for frequency response in program LabView. Afterwards, this thesis focuses on creating a measuring project inside Excel document, with the usage of Visual Basic language for Applications. This project is intended to measure acoustic response, impedance and Thiele-Small parameters of a loudspeaker.
Variable Two-Way Loudspeaker Cabinet - Laboratory Tool
Rehák, Jan ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
The objective of this work is to build a two-way loudspeaker system that will enable changing loudspeaker topology in both vertical and horizontal axes and to suggest two laboratory tasks. The theoretical part of this work will briefly discuss loudspeaker crossovers. Then it will discuss how topology of loudspeakers in a loudspeaker system can affect its behavior at crossover frequency. Frequency characteristics of various loudspeaker baffles will be shown. On these, the effect of a baffle’s exterior on its behavior will be discussed. A two-way loudspeaker system will be designed. The construction process and drawings of each part are also included in this work. The finished product will be tested and, following from these tests, a conclusion will be drawn about the validity of the theoretical assumptions of its design. After that, appropriate parameters of a crossover for the two-way loudspeaker system will be chosen.
Interactive Searching in Online Archive of Visual and Audiovisual Artworks
Kuře, Dominik ; Myška, Vojtěch (referee) ; Schimmel, Jiří (advisor)
This bachelor thesis focuses on development of a web application, which serves as an archive for videos. Each video has a certain amount of keywords. The application uses an already created database and a preinstalled server on which the videos are uploaded. The database was given to the author by his supervisor. Searching through the archive can be done by inputting an expression into a search bar or through a variation of filters that are based on information about each video. The results and the database as a whole are graphically represented by charts, which change their form based on given data. Videos can be played in a video player and a list of similar videos is generated. The list is based on keywords which the videos have in common. The main technologies used in the application are Node.js, React and MariaDB. A good amount of libraries are used for this application, allowing JavaScript to be the primary programming language in all phases of development. The text of this bachelor thesis can be dividen in two parts - theoretical and practical. The first part describes all the technologies and libraries used in the application. An in depth approach was taken especially on those parts of each library which are actually being used in the practical. Apart from the necessary technologies, the reader will be also introduced to libraries and systems which help a programmer with his work such as automatic formatting of code and it's backup, saving different versions of the code or adding static datatypes into JavaScript through TypeScript. The theoretical part should give the reader a summary of how browser applications work and communicate with each other. In the practical part an entire application will be built from scratch. The application will connect four different servers - front-end, back-end, database server and a server storing the videos - and allow them to communicate accordingly. The bachelor thesis also contains information about using different controllers for manipulating the browser.

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