Why bundengan musicians always drench their instruments prior to playing

Abstract

Bundengan is an indigenous musical instrument from Indonesia. It evolved from a bamboo-woven dome originally used by duck herders as a portable shelter during rain and sun. By embedding strings and bars into the dome, the herders turned this shelter into a unique instrument, under which they sit and play music. Bundengan musicians have learned from experience that the instrument sounds better when played under the rain. Nowadays, they use various ways to drench their instruments prior to playing, such as soaking it in fish ponds or putting it under the shower. We explore the physics of why wetter bundengan sounds better. First, we analyze the construction steps of the bamboo dome: the weaving of the bamboo splits, the bending of the woven splits, the layering of bamboo culm sheaths on the woven splits, and the deformation of the sheaths during wetting. Second, we analyze the coupling between the mechanical vibrations in the dome and the acoustical waves from the instrument. Certain conditions of the coupling may lead to an evanescent acoustical field dominating over the radiating acoustical field, which may explain why the best bundengan sound is confined only to under the dome, where the musicians sit.