Laboratory measurements on free reeds from the reed organ, accordion, and khaen

Abstract

Several series of experimental measurements have been made on the motion of air-driven free reeds. These include individual reed organ reeds mounted on a laboratory wind chamber, accordion reeds mounted on the accordion reed block, and khaen reeds in individual bamboo pipes, in which the symmetric free reed is coupled to the pipe resonator. Measurements of reed displacement and velocity as a function of time have been made using a variable impedance transducer and a laser vibrometer system. Additional measurements made for each type of reed include sound pressure and air flow waveforms, as well as variation of sounding frequency and amplitude of vibration with blowing pressure. In comparing the sound pressure and air flow waveforms among the various types of reeds or for the same reed at different blowing pressures, differences can be understood in terms of the configuration of the reed and reed frame system and the amplitude of reed vibration. Some of the results can be interpreted in terms of simple theoretical models.