和太鼓の振動分析

Abstract

A drum has been used as a tool to produce large sound by which a simple information or a signal can send to the place far beyond our vocal sound can reach. In 1877,the vibration of a kettle drum is first analyzed by Lord Rayleigh. As for Japanese drum, having circular membranes streched over both ends of a wooden vessel, an experimental approach was carried out by OBATA et al. in 1933. In this paper, a Japanese drum is theoretically discussed as a coupled vibration system which causes to produce an amplitude modulated sound. To confirm above phenomenon, two types of drum are employed, the one is an ordinary wooden drum, and the other is a drum with aluminium body. Considering sound decay curve for some lower vibration mode, a periodic amplitude fluctuation can be found in both type of drums.