Evaluation of Dynamic Young's modulus and Attenuation Parameter of Woods for Sao of Sanshin and Acoustical Evaluation as Musical Instrument

Abstract

Sanshin is a traditional Okinawan musical instrument and it has been thought that the sao (neck) is the most important part for the timbre by the craftsman and the players. However, scientific research for the woods which are used for sao has not been conducted very often. Furthermore, the woods for sanshin are gradually nearing depletion and the demand of alternate woods has increased. The scientific evaluation of the acoustical performance of the woods would enable the appropriate material selection of the woods for sanshin, and would also be useful for the selection of alternate woods. In this research, Ryukyu kokutan (Diosphyrosferrea), isunoki (Distylium racemosum), and mokumaou (Casuarina equisetifolia, as a candidate for alternate woods) were selected. Samples were tested by conducting the free deflection vibration method at both ends. After the tests, sao were manufactured by the craftsman using these woods and the acoustical characteristics were evaluated as an actual sanshin. As a result, the trend of the attenuation depending on the types of the woods was consistent with the vibration tests of the raw wood and the acoustical evaluation by sanshin. This result suggests that the performance as the sao of sanshin could be evaluated in a state of raw wood. Also, the feasibility of mokumaou as an alternate wood of sao was confirmed.