Investigation of the effect of the violin top plate thickness on bridge mobility and sound radiation

Musical instrument making is an interdisciplinary field with an intricate relationship with mathematics, geometry, chemistry, physics/acoustic physics, etc. How the materials used in instrument making will affect the sound and timbre and the methods of selecting and processing these materials is a significant problem. Making organic materials such as wood, which has no stable properties (especially in parts with direct effects such as acoustic plates) according to standardized, predetermined thickness measurements, is sometimes sufficient to achieve successful results. To make these measurements healthy, some scientific research methods, formulas, and analyses should be used to determine the desired dimensions. However, there are also some traditional methods based on experience. For example, many instrument makers, with an act passed down through the master-apprentice relationship, dating back to the times when there were no technological possibilities in the past, perform a measurement based solely on experience (trial and error methods) by stretching the soundboard by hand and tapping it with their fingers, tuning according to the sound produced, or taking ancient violin plates as an example. These methods, which can work at an average level, only sometimes yield results and are only sufficient for obtaining higher quality results. The fact that these tuning methods are subjective methods without scientific data and that it is difficult or even impossible to archive them as instrument makers have experienced data/sources from the past to the present has made itself felt as a deficiency in the literature. In the experiments conducted in this thesis study, unlike subjective methods, the elasticity moduli of the woods to be used for violin top plates were calculated in the first place. With the obtained data, the top plates of student, orchestra, and soloist violins were determined. Chladni analysis was applied to the free top and back plates to obtain the reference mode shapes and resonance frequencies that are considered as references in violin acoustics. Subsequently, the top plates were sequentially attached to the violin bodies and the violins were strung, and Chladni analysis was repeated for the resonating violin plates. In addition to these experimental modal analysis studies, bridge mobility and sound radiation analyses were applied to all violins. At the end of the research, resonance frequencies and mode shapes of all violins were obtained. It was determined which frequencies were effective to what extent in the sounds emitted from violins with only different top plates. Keywords: Violin Acoustics, Musical Instrument Making, Chladni Analysis, Mobility Analysis, Sound Radiation, Experimental Modal Analysis, Mode Shape, Mode Frequency