MSc Thesis – A Novel Method For Controlling Vibrational Properties Of Oud Soundboard Constructed With Acoustic Measurement Methods

Abstract – The main purpose of manufacturing musical instruments is to produce instruments that have sound at desired quality. The main problem here is determining the methods for selecting and processing the material that will be used to achieve this sound. It is not sufficient to use pre-determined thickness values for processing of the wood, a material which does not possess constant properties. Properties such as elasticity, density, vibration should be taken into account and important parts such as soundboard, braces should be tuned accordingly. In other words, these parts should be shaped from appropriate materials, in accordance with free vibrational patterns and frequencies. Some of the instrument makers tune the soundboard by flexing with their hands and by listening the sound when they knock it with their fingers. Since this way of tuning is subjective and it is difficult to archive and transfer, a quantitative method to explain the process is desirable. In this study a method for producing the soundboard and selection of the wood material is proposed which is based on quantitative measures. Chladni Method was used for observing surface vibrational patterns and Tapping Method was used for measuring the natural frequencies of the wooden material. Additionally, a setup for computer-controlled plectrum strokes was designed in order to acquire the sound records of the ouds in a standard way. As a first step a soundboard is prepared from the wooden material which was selected based on measurements of elasticity and density. The free vibrations of this soundboard was measured for six different height values of the braces. For each change in the soundboard, it was attached to the oud, the strings were placed and the sound produced by the instrument was analyzed. According to the findings of the study, the soundboards having longer resonance times resulted in longer sounds with stronger harmonics in the instrument. When free vibrations of the soundboard were analyzed, it was seen that the conflicts superpositions in frequency values shortened the sound length. Additionally, it was observed that the free vibrations of the soundboard have consistent effects on the timbre. In conclusion, this study proposes a way to tune the soundboard of oud by using acoustic measurement techniques, for the first time. It is thought that the proposed method will contribute in the efforts to produce high quality sounds and to establish quality standards in oud and all other stringed musical instruments in Turkish Music.