|
|
Analýza vibro-akustických vlastností kobylek piana
Doskočil, Tadeáš
The subject-matter of the diploma thesis is the research of effects of acoustic properties which are used for making piano bridges. In this work technological process of different piano bridges is discussed and problems related to it. In the next step materials like: maple, hardrock maple, laminated maple, laminated maple and mahagony, ebony, beech, laminated beech, crosswise glued beech, laminated beech and lignamon and hornbeam are compared in the aspect of acoustic properties. The differences among acoustic properties were searched by non-destructive methods with the help of device metering and final elements method. A frequence analysis of embedded grand piano soundboard was made. Statically eminent differences of acoustic properties were found among metering samples. There were found out the own frequences of metering soundboard and frequency spectrum in particular parts of piano bridge
|
|
|
Acoustic properties of word stress in read Czech English
Liska, Jan ; Volín, Jan (advisor) ; Skarnitzl, Radek (referee)
key words: Czech English, foreign accent, word stress, word accent, stressed syllable, duration, f0, acoustic cues. This study investigates the acoustic properties of word stress in Czech English. The notion of foreign accent is introduced and its drawbacks are presented. Further on the various influences on the perceived degree, or strength, of foreign accent are discussed. Faulty realization of word stress is identified as one of the factors that contribute to unintelligibility of non-native speech (Benrabah, 1997; Hahn, 2004; Cutler, 1984). In Chapter 2 we compare the results of studies that used speakers of a variety of languages and form a basic theory on the acquisition of acoustic cues to word stress. We are mostly interested in f0 and duration. This theory, based on the feature hypothesis (McAllister et al., 2002 in Lee, Guion & Harada, 2006), states that languages that have a similar stress system to that of English (Dutch, Arabic) use their native cues to signal word stress, while non-contrastive languages (Vietnamese, Czech) prefer cue/s that are phonologically active on segmental level in their native language. Speakers of Vietnamese, a tone language, were found to prefer f0 over duration (Nguyen, 2003), so for Czech, a language that uses phonological vowel duration, it is expected that...
|
|
|
Vliv čalounických materiálů na akustický komfort v interiéru
Schmidtová, Terezie
This thesis documents the possibilities of elements application in interiors in order to improve the acoustic characteristics of the space and it analyses the acoustic issues in contemporary interior and factors that affect it. The aim is to compare the acoustic absorption of selected types of filling materials and upholstery composition used in its production. The thesis includes a description of sample preparation, a procedure of measurement in an impedance tube, results processing to determine the sound absorption of tested materials and a measurement of foam cells sizes using microscope and Visiocell program. Acquired values were compared with each other.
|
|
|
Vliv doby a teploty paření na pružnostní a pevnostní charakteristiky dřeva buku
Jakeš, Ondřej
This diploma thesis primarily focuses on thermal modification of wood with superheated steam and its effect on elasticity and strength. The sample tested was 200 pcs of bending samples and 200 pcs compressive samples of European beech. These samples were divided into ten groups. One group was referential and the remaining nine groups were modified using different temperatures and during different time intervals. The main goal was to determine density, modulus of elasticity and rupture and to discover their dependence on the chosen mode of modification. The next part contains the analysis of the effect of thermal modification with superheated steam on the acoustic properties and the colour of wood. In the last part, the mass loss and the change in equilibrium moisture content was analysed in relation to the modification mode.
|
|
|
Možnosti snížení navlhavosti dřeva a přestupu vlhkosti do dřeva užitého v konstrukci rezonanční desky hudebního nástroje
Zatloukal, Petr
This theses is focused on possibilities of sorption properties decrease of musical instruments soundboards. This task should be solved with respect to sustainability of previous acoustics properties or their improving. The resonance wood specimens has been fabricated and conditioned to the relative humidity of 40 % The specimens were divided into three groups. The first one with natural properties, the second one treated by the temperature of 180 °C and the last one was treated by 200 °C. Specimens were conditioned all together to the relative humidity of 60 % and at the last step at 80 %. The conditioning was isothermal with the temperature of 20 °C. Swelling and hygroscopicity establishment was based on dimensions and weight measurement during conditioning of specimens. The first, second and longitudinal natural oscillation frequency of the specimens were determined by free-free resonant frequency method. Longitudinal and transversal sound propagation velocity were measured using Fakopp Ultrasonic Timer. Dynamic Young’s modulus (E´L,E´RT), dynamic bend Young’s modulus (Eb), acoustic constant (KL, KRT), characteristic impedance (ZL, ZRT), acoustic conversion efficiency (ACEL, ACERT), relative acoustic conversion efficiency (RACEL, RACERT) and damping coefficient (tan δ) were determined using the measured data. The treatment by 180 °C caused the decrease of volume swelling, which was 7,4% lower after the treatment. The hygroscopicity decreased by 2,8%. The treatment by 200 °C decreased swelling by 8,5% and the hygroscopicity by 4,3%. The different results of both treatments were observed in case of longitudinal sound velocity. In case of 180°C treatment the value of longitudinal sound velocity decreased by 1,6 %, whereas after treatment by 200 °C the increase by 2,1% was found. Acoustical properties E´, Eb, K, Z, ACE, RACE were decreasing due to the higher moisture content and tan δ was increased. Heat treatment by 180 °C has not significantly affected acoustical properties and sound velocity but the treatment by 200 °C caused their increase.
|
|
|
Vliv defektů ve dřevě na stanovení rychlosti šíření zvuku ve dřevě v čerstvém stavu
Vobořil, Matěj
This bachelor research deals with determining the speed of sound propagation in wood in fresh state. Specifically, maple milk (Acer platanoides L.) was investigated. Acoustic properties were determined by the non-destructive method thanks device from Fakopp company. These were an ultrasonic timer and a microsecond timer. Sensors like SD02, TD45 and US10 were selected for measurement. The primary objective was to determine the velocity of the sound signal propagating both 1 m long trunk and the 20 x 20 x 300 mm sized samples and to determine the effect of wood defects on that velocity. The secondary objective was to determine the dependence of the measured results depending on the world side.
|
|
|
Acoustic properties of word stress in read Czech English
Liska, Jan ; Volín, Jan (advisor) ; Skarnitzl, Radek (referee)
key words: Czech English, foreign accent, word stress, word accent, stressed syllable, duration, f0, acoustic cues. This study investigates the acoustic properties of word stress in Czech English. The notion of foreign accent is introduced and its drawbacks are presented. Further on the various influences on the perceived degree, or strength, of foreign accent are discussed. Faulty realization of word stress is identified as one of the factors that contribute to unintelligibility of non-native speech (Benrabah, 1997; Hahn, 2004; Cutler, 1984). In Chapter 2 we compare the results of studies that used speakers of a variety of languages and form a basic theory on the acquisition of acoustic cues to word stress. We are mostly interested in f0 and duration. This theory, based on the feature hypothesis (McAllister et al., 2002 in Lee, Guion & Harada, 2006), states that languages that have a similar stress system to that of English (Dutch, Arabic) use their native cues to signal word stress, while non-contrastive languages (Vietnamese, Czech) prefer cue/s that are phonologically active on segmental level in their native language. Speakers of Vietnamese, a tone language, were found to prefer f0 over duration (Nguyen, 2003), so for Czech, a language that uses phonological vowel duration, it is expected that...
|
|
|
Analýza vlastností součástí pianinové skříně vyrobených z vláknité desky nebo laťovky
Doskočil, Tadeáš
The subject-matter of the work is research of effects that upright piano panels have on its sound. The removable panels were made of medium-density fibreboard, Purenit, Multiplex or decking. The differences between them were investigated through device measurement of samples of these materials. The variation of influence between materials of different upright piano panels was observed and measured by device measurement. Finally, the difference between using dissimilar material composition was subjectively judged, directly on the finished instrument by piano-maker specialists and intoners.
|
guest ::
