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The analysis of acoustic properties of innovative wood-based materials
Svojanovský, Jan ; Nop, Patrik (referee) ; Jirásek, Ondřej (advisor)
The content of this work is research of innovative wood-based materials in the acous-tic perspective. Basically, the goal is to determine the influence of the internal structure of the wood-based material on variables, which are sound speed, acoustic resistance, or acous-tic constant. In total were measured 15 samples, each one was made in a different way. Each sam-ple was weighted, and the length of its sides was measured. By using the ultra sonic timer, it was measured the time of the sound impulses, which go through the samples in all of their axes for the purpose of observation the influence the fibers on speed of sound in the materi-al. The next thing to do was to determine another magnitude, which describe acoustic of the material. All measurements were taken in room conditions (room humidity). Six of the sam-ples, which were randomly selected from those 15 samples, were measured once again after two weeks. In those two weeks were all the samples saved in air-conditioned place in which was the room humidity distinct lower. In the end all the samples were compared with each other and they were also com-pared with materials which are commonly used in production of musical instruments or acoustic components. Possible use in the music industry was assigned to each sample.
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The Analysis of impedance properties of the bridge in string instruments
Němec, Petr ; Nop, Patrik (referee) ; Jirásek, Ondřej (advisor)
It is a known fact that stringed instruments bridge makes an important part of "acoustic circuit" of their bodies. Bridge acts as an acoustic filter which has the biggest impact on 2 – 6 kHz band and high frequency bands. To find the connection between the impact of a specific acoustic and mechanical properties of a bridge and acoustical behavior of the entire instrument remains as a matter of further exploration. Aim of this thesis is to find the mentioned relations of a chosen materials in an accordance to their mechanical properties within a full range of materials with common bridge properties. The experiments are designed to determine mechanical and acoustic properties of chosen materials which are then used to fabricate bridges. Subsequently the acoustical behavior of instruments with chosen bridges is determined. Based upon these findings we propose specific solutions and suggest further research.
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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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The Analysis of impedance properties of the bridge in string instruments
Němec, Petr ; Nop, Patrik (referee) ; Jirásek, Ondřej (advisor)
It is a known fact that stringed instruments bridge makes an important part of "acoustic circuit" of their bodies. Bridge acts as an acoustic filter which has the biggest impact on 2 – 6 kHz band and high frequency bands. To find the connection between the impact of a specific acoustic and mechanical properties of a bridge and acoustical behavior of the entire instrument remains as a matter of further exploration. Aim of this thesis is to find the mentioned relations of a chosen materials in an accordance to their mechanical properties within a full range of materials with common bridge properties. The experiments are designed to determine mechanical and acoustic properties of chosen materials which are then used to fabricate bridges. Subsequently the acoustical behavior of instruments with chosen bridges is determined. Based upon these findings we propose specific solutions and suggest further research.
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The analysis of acoustic properties of innovative wood-based materials
Svojanovský, Jan ; Nop, Patrik (referee) ; Jirásek, Ondřej (advisor)
The content of this work is research of innovative wood-based materials in the acous-tic perspective. Basically, the goal is to determine the influence of the internal structure of the wood-based material on variables, which are sound speed, acoustic resistance, or acous-tic constant. In total were measured 15 samples, each one was made in a different way. Each sam-ple was weighted, and the length of its sides was measured. By using the ultra sonic timer, it was measured the time of the sound impulses, which go through the samples in all of their axes for the purpose of observation the influence the fibers on speed of sound in the materi-al. The next thing to do was to determine another magnitude, which describe acoustic of the material. All measurements were taken in room conditions (room humidity). Six of the sam-ples, which were randomly selected from those 15 samples, were measured once again after two weeks. In those two weeks were all the samples saved in air-conditioned place in which was the room humidity distinct lower. In the end all the samples were compared with each other and they were also com-pared with materials which are commonly used in production of musical instruments or acoustic components. Possible use in the music industry was assigned to each sample.
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Measurement of acoustic input impedance of the human vocal tract models
Radolf, Vojtěch ; Dlask, P. ; Otčenášek, Z.
Input acoustic impedance of the human vocal tract models made of plexiglass was measured using the measurement system BIAS 6. Three models A, I, U for vowels /a:/, /i:/ and /u:/ had simplified rectangular shape of the channel with constant height 20 mm. The fourth model A2D had elliptical channel shape. Resulted resonance frequencies were within the known ranges of formant frequencies of the vowels. The resonances of default configurations varied for different boundary positions in relation to measuring microphone in the range of 0.5 %, 3.9 %, 2.1%, 6.7 % for the models A2D, A, I and U, respectively. The resonances of direct and reversed models with the output closed differed in the range of 0.5 % and 1.8 % for A2D and A model, respectively. The measured and computed resonances differed in the range from 3.8 % for A2D to 14.6 % for the model I.
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