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Impedance tube for measuring sound absorption coefficient and transmission loss coefficient
Hodinka, Tomáš ; Balík, Miroslav (referee) ; Skvaril, Šimon (advisor)
The goal of this thesis is the design and manufacture of the mechanical and electrical components of the impedance tube. The impedance tube is a tool used in laboratories, that has its parameters dictated by norms. On one side of this enclosed airtight tube is a speaker, and on the other the measured material. By switching some additional parts, the tube is capable of measuring not only the acoustic absorption, but also sound penetration. Impedance tube is made, so that it is robust, easy to manipulate and use, and easy to store. The designed impedance tube can measure the sound penetration of any material, that is up to 50mm in thickness, and the acoustic absorption of materials that are up to 120mm in thickness. Parts of the tube, that are directly welded to the tube itself are made of the same metal that the tube itself is, and the speaker enclosure is made from plywood. Along with the assembly of the impedance tube, a complete and detailed drawing documentation for future recreation is added, along with a suitable amplifier and all peripherals necessary for measurements.
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Impedance Tube for Measuring Sound Absorption Coefficient
Raška, Adam ; Sysel, Petr (referee) ; Schimmel, Jiří (advisor)
This thesis, consists of summering basic knowledge about absorption factor, methods for its measuring and construction of impedance tube for measuring with chosen method. Besides that, this thesis i salso about measuring absorbtion factor of available materials in this tube, and proposing laboratory task about absorbtion factor measurement, which should use crafted measuring equipment.
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Determination of the Material Acoustic Impedance
Vozárová, Juliana ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This diploma thesis deals with the determination of the material acoustic absorption in an impedance tube. The aim of the work is to propose a measuring experiment and to design measuring device with the intention of reducing costs. The aim is to carry out a measuring experiment on a manufactured measuring device. The results of the experiment are evaluated in terms of meeting the requirements formeasuring device. The results of the tested materials are compared with the values from the supplier.
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Determination of Acoustic Properties of Sound-Absorbing Materials
Ďurica, Matej ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This diploma thesis is focused on experimental determination of acoustic absorption of four different material samples. The aims of the work include: research on the given issue, determination of the procedure for the performance of a technical experiment and modification of the measuring device for the determination of acoustic absorption. The performed experiments were evaluated and the results of the sound absorption coefficient were compared with the values given by the manufacturer. Sensitivity analyzes of the experiments were performed.
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Computational modelling of high-frequency noise inside cabin of aircraft EV-55M
Straka, Martin ; Pellant, Karel (referee) ; Švancara, Pavel (advisor)
This thesis describes methods of high frequency noise and vibrations computation of cabin part of EV–55M (aircraft developed by Evektor Kunovice). There is a brief summary of methods used for determining high frequency noise and vibrations in the first part of the thesis. Detailed explanation is given for Statistical Energy Analysis (SEA) which is nowadays the most dominant method in this area. The energy balance equation is derived in this chapter and SEA parameters such as modal density, damping loss factor, coupling loss factor and power input are introduced here. Next part deals with main noise sources of propeller driven and jet aircraft and passive and active noise controls are discussed. Practical part of this thesis deals with modeling aircraft EV–55M fuselage using VA One SEA module. Two models were created. First of them is only an outside fuselage with aircraft flooring and the second one is extended by interior trim panels and is applicable for simulation of noise control treatments. Computational modeling is accompanied by experimental measurement of passive noise control material characteristics. Postprocessing of information obtained from impedance tube measurement was performed in FOAM – X. Determined characteristics of porous material were used as inputs to VA One and reduction of sound pressure level in fuselage cavities by using noise control treatment was found. In conclusion there is a summary of noise transmission paths from sources to interior cavity and some treatments of them are simulated
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Measuring system for acoustic characterisation of materials
Plánka, Mikuláš ; Havránek, Zdeněk (referee) ; Klusáček, Stanislav (advisor)
The diploma thesis deals with the measurement of acoustic parameters of the material using the B\&K 4206 impedance tube, specifically the absorption and reflection coefficients. The theoretical part provides a basic overview of the measurement methodology and a description of measurement quantities related to acoustic materials characterization. The measurement procedure using the PULSE LabShop software is also described in this work. The main focus of this thesis is the design and implementation of a custom open measurement system created in LabVIEW used to determine the aforementioned materials parameters. The results of the measurements using the custom implementation and the PULSE LabShop software are compared and evaluated in this diploma thesis.
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Determination of Acoustic Properties of Sound-Absorbing Materials
Ďurica, Matej ; Řehák, Kamil (referee) ; Prokop, Aleš (advisor)
This diploma thesis is focused on experimental determination of acoustic absorption of four different material samples. The aims of the work include: research on the given issue, determination of the procedure for the performance of a technical experiment and modification of the measuring device for the determination of acoustic absorption. The performed experiments were evaluated and the results of the sound absorption coefficient were compared with the values given by the manufacturer. Sensitivity analyzes of the experiments were performed.
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