Bamboo pipe wall vibrations in Asian free reed instruments.
James P. Cottingham · The Journal of the Acoustical Society of America · 2010
Wall vibrations in the bamboo pipes of the Asian free reed mouth organs have been investigated. The pipes studied include quasi-cylindrical examples from a khaen built in northeastern Thailand and some pipes from a Southeast Asian free reed gourd pipe. Modal frequencies and mode shapes of a number of the pipes were measured using mechanical excitation. The modes of vibration of these pipes were also simulated using measured physical properties of the bamboo, which has a relatively low density and elastic modulus, and a significant difference between the elastic moduli parallel and perpendicular to the grain. Vibration of the pipe walls was also studied for the mechanically blown reed-pipe combination. Measurements of pipe input impedance have been made, showing changes occurring as a result of damping the pipe vibrations. Possible effects of wall vibrations on the radiated sound have also been explored.