Abstrak/Abstract |
One of the most intriguing elements of the bundengan musical instrument is its shell-shaped resonator, called the kowangan. The kowangan structure is built using a woven bamboo lattice that is coated with bamboo culm sheaths. To better understand how the kowangan works, we performed an Experimental Modal Analysis, where we excited the kowangan structure with an impact hammer and measured the resulting vibrations with an accelerometer. Our data show that the average value of the first, second, and third natural frequencies are 1068.2 Hz, 1150.3 Hz, and 1202.5 Hz, respectively. However, the data also show that each part of the kowangan structure exhibits different natural frequencies, such that the measured first, second, and third natural frequency have very high standard deviations, i.e. 225.1 Hz, 192.9 Hz, and 195.8 Hz, respectively. These data indicate that the kowangan is a semi-rigid structure, where the rigidity is strongly influenced by how the kowangan is built: the weaving of the bamboo splits, the coating of the bamboo culm sheaths, and even the wetting of these sheaths. |