|
| |
|
|
Acoustic Signal Recording and Processing Using B-Format Technology
Kurc, David ; Balík, Miroslav (referee) ; Schimmel, Jiří (advisor)
This bachelor’s thesis is focused on the system of recording and processing of acoustics signals called Ambisonics. It describes single sections of this system in the chain of acoustic signal processing. At most it is aimed at the B-format technology as the main ambisonic instrument, its encoding from the signals recorded with the special microphone capsule of the soundfield type or with help of encoding equations and its decoding into single speaker channels of various speaker arrays. The UHJ transmission format is also mentioned. The application B-format Decoder was created in the MATLAB programming environment. It consists of several functions and has friendly user interface, which provides the processing and decoding of B-format components for the speaker array with entered parameters. Among others this interface ensures loading, displaying, analysis and playback of source and resulting acoustic signals.
|
|
|
Simulations of auditory space and azimuth&distance of sound source, for multichannel sound systems
Orlovský, Kristián ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
This thesis is aimed at simulation of auditory space. It describes the most frequently used panning method: Vector Base Amplitude Panning. Also is focused on image source method, which allows computing the parameters of direct sound wave and reflections in rectangular room. This method is compared with ray–tracing method, which is also often used. It deals with the matter of the frequency – dependent absorption of materials in reflection of the sound wave against the wall. On the basis of these information two applications were designed in MATLAB development environment. The first one allows the simulation of auditory space. The other one is the application for sound source panning by its azimuth and distance.
|
|
| |
|
|
Nanometric vibrometry
Ševčík, Michal ; Schimmel, Jiří (referee) ; Škarvada, Pavel (advisor)
This thesis deals with the precise measurement of distances in nanometer range at ultrasonic frequencies for the purposes of vibrometry. The paper is primary focused on~nanometric displacement measurement methods. First the thesis deals with the physical phenomena based on light in the theoretical section. This includes interference of light, index of refraction, polarization, interferometry and more. Understanding of these physical laws is crucial for design and assembling of the interferometer. Subjects of interferometric method for precise and fast measurement of the nanometric displacement and vibration are discussed. Interferometer components such as lasers, photodetectors and optical elements are described are described in the final part of this section. Practical section of thesis can be divided into two parts. The design and assembling issues are discussed in the first section. Many problems which I had to solve are described. Control software and implementation of the signal processing is the subject of the second part. I met with particular problems such as phase unwrapping. I solved this problem of discontinuous phase field with user written algorithm. Finally the graphical user interface was created. Using assembled interferometer and written software application I measured vibration of Langevin transducer on ultrasonic frequencies.
|
|
|
Using masking effects for audio data watermarking
Kabourek, Jiří ; Schimmel, Jiří (referee) ; Zezula, Radek (advisor)
In this work is presented technique for embedding digital watermark in digital audio signals. Digital watermark must be imperceptible and should be robust against attacks and other types of distortion. Algorithm is implemented for embedding digital watermark using technique spread-spectrum and psychoacoustic model ISO-MPEG I layer I. Robustness was tested for filtering signal, MP3 compression and resample method.
|
|
|
Sound panning in multichannel sound systems
Orlovský, Kristián ; Schimmel, Jiří (referee) ; Balík, Miroslav (advisor)
This thesis is aimed at simulation of auditory space. The first part is based on theoretical information and explains two of the most frequently used sound panning methods: Vector Base Amplitude Panning and Ambisonics. It shows the ways for sound panning by these methods. In next step are methods compared based on theoretical information and simulations in Matlab environment and one most suitable method is chosen for using in second part. This part describes image source method which enables parameters computation of direct sound wave and optional number of early reflections in rectangular room. Also is focused on problem of frequency dependent reflections. In conclusion it offer knowledge obtained by simulation of different auditory spaces with different topology.
|
|
|
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.
|
|
|
Laboratory Practices Focused on Loudspeaker System Design
Vydarený, Ján ; Balík, Miroslav (referee) ; Schimmel, Jiří (advisor)
This work deals with creating the bases for the laboratory tasks of designing the speaker system. The theoretical part explains the TS parameters and the equations for their calculation, the different types of sounding and switches. The work deals with selecting a suitable high-tone speaker to the specified low-tone speaker. Closed and bass reflex simulations were performed in the LspCAD. Similarly, simulation of the loudspeaker network was created in this program too. A loudspeaker box, crossover and subsequent measured parameters of the resulting repro system were produced. The last step was to modify the lab instructions
|
|
|
Modern Methods of Time-Frequency Warping of Sound Signals
Trzos, Michal ; Rakús, Martin (referee) ; Průša, Zdeněk (referee) ; Schimmel, Jiří (advisor)
Tato práce se zabývá reprezentací nestacionárních harmonických signálů s časově proměnnými komponentami. Primárně je zaměřena na Harmonickou transformaci a jeji variantu se subkvadratickou výpočetní složitostí, Rychlou harmonickou transformaci. V této práci jsou prezentovány dva algoritmy využívající Rychlou harmonickou transformaci. Prvni používá jako metodu odhadu změny základního kmitočtu sbírané logaritmické spektrum a druhá používá metodu analýzy syntézou. Oba algoritmy jsou použity k analýze řečového segmentu pro porovnání vystupů. Nakonec je algoritmus využívající metody analýzy syntézou použit na reálné zvukové signály, aby bylo možné změřit zlepšení reprezentace kmitočtově modulovaných signálů za použití Harmonické transformace.
|
guest ::
