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Microphone Array for Estimation of Direction of Arrival of Sound
Kubišta, Ladislav ; Balík, Miroslav (referee) ; Schimmel, Jiří (advisor)
This bachelor's work describe detection of direction receiving sound by analizing of the sound. Work is based on methods of time delay estimation. Programmed algorithm of estimation direction works on cross–correlation and some selected cross–correlation methods. Results of measuring, as programming sound, so sound recorded in laboratory conditions and real enviroment, are mentioned in conclusion. All calculations were done by platform Matlab
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Evaluation of Traffic Noise
Mejzlík, Martin ; Spies, Karel (referee) ; Kudrna, Jan (advisor)
This thesis deals with issue of traffic noise, its measurement and data evaluation. Theoretic part of my work concretes basic information about acoustics and also describes and analyzes traffic noise sources of tire/pavement. Next part deals with quite pavement and with measurement methods of traffic noise. Practical part of my thesis contains description, results and evaluation of realized measurement with methods CPX and SPB.
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Hybrid Microphone Preamplifier
Valach, Ondřej ; Hanák, Pavel (referee) ; Koton, Jaroslav (advisor)
The diploma thesis deals with the design of hybrid microphone preamplifier with stepless choice of amplification technology between active part using tube or semiconductor elements. Before the design, the basic physical relations of electroacoustics were described. Problems of connection of audio devices, their voltage and noise conditions. At last technical properties of microphones and tubes were described. In the practical part, the overall structure of the hybrid preamplifier is designed and the goals of the thesis are set. This is followed by a detailed design of the preamplifiers. From input circuits through individual amplifier stages of the semiconductor and tube sections to the output of the device. Much of the circuit was tested by software simulations. Based on the results obtained in the design of the signal part of the preamplifier, the power circuits were designed. Finaly the preamplifier functionality was verified by measurement on the Audio Analyzer.
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Digital microphone signal processing
Vykydal, Martin ; Macho, Tomáš (referee) ; Havránek, Zdeněk (advisor)
The aim of this work is to implement digital filters into programmable gate array. The work also includes a description of the MEMS technology, including comparisons with the technology of MEMS microphones from various manufacturers. Another part is devoted to the Sigma-delta modulation. The main section is the design and implementation of digital CIC and FIR filters for signal processing of digital microphone, including simulation and verification of properties of the proposed filter in Matlab.
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Processing of heart sounds signals
Němcová, Simona ; Matějková, Magdaléna (referee) ; Vondra, Vlastimil (advisor)
This bachelor thesis is focused on the heart sound signal. It describes the principles of hear sound formation, measurement methods and especially the analysis of the measured phonocardiography signal. In the practical part of this thesis, the algorithm for detecting the first and the second heart sounds is designed by using MATLAB software. Its principle is realized in finding maximum or center of gravity in the filtered phonocardiography signal.
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Recognition of vehicles using signals sensed by smartphone
Nevěčná, Leona ; Vítek, Martin (referee) ; Smíšek, Radovan (advisor)
Thanks to the development in recent years, the placement of miniaturized sensors such as accelerometers, gyroscopes, magnetometers, global positioning system receivers (GPS), microphones or others to commercially sold smartphones is increasing. Use of these sensors (which are to be found in the smartphone) for human activity recognition with health care improvement in mind is a discussed theme. Advantages of the use of smartphone for human movement monitoring lies in the fact that it is a device that the person measured carries with them and there are no additional costs. The disadvantages are a limited storage and battery. Therefore, only accelerometer, gyroscope, magnetometer, and microphone were chosen because their combination achieves best results. GPS sensor was excluded for its lack of reliability in sampling and for being energy demanding. Features were computed from the measured data and used for learning of the classification model. The highest accuracy was achieved with the use of a machine learning method called Random Forest. The main goal of this work was to create an algorithm for transportation mode recognition using signals sensed by a smartphone. The created algorithm succeeds in classification of walk, car, bus, tram, train, and bike in 97.4 % with 20 % holdout validation. When tested on a new set of data from the tenth volunteer, the resulting accuracy counted as average form classification recall for each transportation mode reached 90.49 %.
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Design of Portable Audio Recorder
Vávra, Marek ; Bukvald, Jiří (referee) ; Sládek, Josef (advisor)
The aim of this thesis was to design portable audio recorder for professionals and sound enthusiast. The important part of this bachelor thesis was to design simple controlled a endurable high quality device with simple and compact shape. Requirements of professional users were fullfilled by using modern technologies available in the sound industry.
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Transmitter for professional microphone
Árva, Gábor ; Kubíček, Michal (referee) ; Kolouch, Jaromír (advisor)
This project deals with the design of a transmitter in a wireless microphone system, which connects to a microphone through an XLR connector. It contains detailed description of the individual blocks, which are necessary for processing and transmitting the signal received from the microphone. It discusses methods of frequency modulation using a phase locked loop and compares their advantages and disadvantages. As the last, it deals with the antenna selection and its shrinking methods.
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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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