4aMU2. Acoustics of the khaen: The Laotian free-reed mouth organ.

Session: Thursday Morning, June 19

Author: Casey A. Fetzer
Location: Phys. Dept., Coe College, Cedar Rapids, IA 52402
Author: James P. Cottingham
Location: Phys. Dept., Coe College, Cedar Rapids, IA 52402


The khaen is constructed with free reeds mounted in bamboo pipe walls inside a carved wooden windchest. Each reed of the khaen sounds for both directions of air flow (inhaling and exhaling). The reed vibration is strongly coupled to the pipe resonance, and the reed will sound only if a small hole near the reed is closed, causing the resonant frequency of the pipe to be near that of the reed. For some examples of khaen made in northeastern Thailand, variations in frequency and sound spectrum with blowing pressure have been studied, with both positive and negative blowing pressures considered. The relationship between frequency of reed vibration and pipe length has been studied to determine the range of pipe length over which the reed can be made to sound, as well as the amount of frequency shift associated with changes in resonance frequency of the pipe. A comparison is made with a previously reported result that the sounding frequency of the reed-tube combination is higher than the natural resonance frequencies of either the reed or the pipe taken alone. [L. E. R. Picken, C. J. Adkins, and T. F. Page, Musica Asiatica 4, 117--154 (1984).]

ASA 133rd meeting - Penn State, June 1997