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Room Modes in Rectangular Rooms with Complex Impedance Boundaries
Jun, David ; Plasek, Josef ; Rychtarikova, Monika ; Glorieux, Christ
In many calculation approaches in room acoustics, one models the reflection of surfaces via a positive, real absorption coefficient, neglecting the fact that the reflection coefficient can have a non-zero phase. For some sound-absorbing structures such as resonators, this simplification leads to erroneous results, e.g. when room modes are of interest.
This contribution presents an approach for the calculation of room mode frequencies in a rectangular room with complex and frequency-dependent acoustic impedance wall boundary conditions. The results are to be used for auralizations of different scenarios in which the modal behaviour of a room is modified, and for evaluation by listening tests.
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Design of Acoustic Absorbers Using Perforated Boards
Jun, David ; Stejskal, Pavel (referee) ; Kalousek, Lubor (advisor)
Perforated boards are one of the most commonly used elements for the construction of acoustic resonators in the form of walls or ceilings. This diploma thesis focuses on some aspects of the design of these perforated resonators. The main factor considered was the shape of the holes in the plate and its influence on the measured course of the sound absorption coefficient and also on its prediction by commonly available methods. The first aspect of resonator design is to measure the sound absorption coefficient. Within the work, common measurement methods are thoroughly compared and the reverberation room method, which is further used for measuring the produced samples, is presented in more detail. For the purposes of this part, our own hardware and software solution of the measuring set is also developed. Service scripts were written in the Python programming language. The second aspect of the design treated in this work is the choice of the porous infill of the resonator based on its value of airflow resistivity. This value is determined here by the static airflow method and based on the relevant standards, our own measuring device was developed for these purposes. This device was made mainly by FDM 3D printing and was operated by scripts in Python. The third and last of the design aspects described here is the prediction of the course of the sound absorption coefficient of perforated resonators. In this part, the method of electro-acoustic analogy is presented together with the transfer matrix method as described in the literature, which is further supplemented by the introduction of an equivalent radius including the effect of hole elongation in the calculation. The results obtained by the calculation are finally compared with the measurement and the optimization of the calculation is proposed in the form of adjusting the relationship for the end correction factor and for the combination of acoustic impedances of individual layers.
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Recording Studio with Accommodation in Proseč
Jun, David ; Remeš, Josef (referee) ; Kalousek, Lubor (advisor)
The thesis deals with designing a recording studio with accommodation. The object is drafted as a three-level construction built on a slightly sloping terrain. The purpose of the studio is to record primarily artificial chamber music and the accommodation space ought to be provided preferentially to the musicians involved. Attention is paid especially to the space layout and structure of the recording studio. The thesis is based on foreign literature and focuses on unique approaches to designs of absorbent and diffuse elements.
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Measurement of Sound Absorption Coefficient in Impedance Tube
Jun, David ; Nespěšný, Ondřej
The sound absorption coefficient is one of the most common quantities describing the acoustic behaviour of materials and structures intended for use in room acoustics. This contribution first shows a brief overview of techniques for measuring sound absorption coefficient. Special attention is paid to the impedance tube (often called Kundt tube) group of methods. The following is an introduction to the measurement of the transfer-function method and to a developed impedance tube prototype, including both the hardware assembly and the software implementation of the measurement.
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Recording Studio with Accommodation in Proseč
Jun, David ; Remeš, Josef (referee) ; Kalousek, Lubor (advisor)
The thesis deals with designing a recording studio with accommodation. The object is drafted as a three-level construction built on a slightly sloping terrain. The purpose of the studio is to record primarily artificial chamber music and the accommodation space ought to be provided preferentially to the musicians involved. Attention is paid especially to the space layout and structure of the recording studio. The thesis is based on foreign literature and focuses on unique approaches to designs of absorbent and diffuse elements.
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Application of transfer pricing methods for reinsurance
Jun, David ; Francírek, František (advisor) ; Finardi, Savina (referee)
The aim of this diploma thesis is to make a model comparability analysis of controlled transactions within the reinsurance of insurers and to recommend appropriate transfer pricing methods based on defined assumptions. The work is divided into three parts. The first part deals with transfer pricing issues, focusing on comparability analysis and recommended transfer pricing methods according to the Transfer Pricing Guidelines for Multinational Enterprises and Tax Administrations formulated by Organization for Economic Co-operation and Development (Guidelines OECD). The second part describes the basic knowledge and routine practice for the area of reinsurance connected to the transfer of insurance risks. The last part combines the first two chapters, i.e. application of transfer pricing methods in the light of the comparability analysis according to the Guidelines OECD for reinsurance of insurers. The application itself is implemented through the model comparability analysis in order to recommend appropriate transfer pricing methods, i.e. in accordance with the arm's length principle.
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Development of taxation in selected European countries
Jun, David ; Vítek, Leoš (advisor) ; Bayer, Ondřej (referee)
This bachelor thesis examines the development of taxation in selected European countries, namely in the Czech Republic, the Slovak Republic, Hungary, Germany, the United Kingdom and Sweden. It is described by tax indicators -- tax ratio and implicit tax rates and also via ratios of each tax chapter on total tax revenues -- tax structures. Indicators and tax chapters are in detail explained including their calculation. The second part, the analytical one, examines their development in time between selected countries and the overall development within OECD and EU members with detail look on the Czech Republic.
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