Blown-closed free reeds with and without pipe resonators.
James P. Cottingham · The Journal of the Acoustical Society of America · 2009
The Asian mouth-blown free reed instruments are of ancient origin and use a symmetric free reed coupled to a pipe resonator. The reed behaves as a blown-open or outward striking reed, with playing frequency below both the resonant frequency of the pipe and the natural frequency of the reed. Although these instruments were known in Europe when the Western free reed family originated about 200 years ago, it does not appear that the mechanism used in the Western instruments was copied from them. In Western free reed instruments the reed tongue is offset from the opening in the frame, permitting operation on only one direction of air flow. Pipe resonators are not required and generally not used. If one of these reeds is coupled with a pipe, the sounding frequency can, within certain limits, be pulled to match the pipe frequency, and it behaves as a blown-closed or inward striking reed, with playing frequency below both the resonant frequency of the pipe and the natural frequency of the reed. This paper summarizes recent experimental research on the blown-closed free reed, with or without coupling to a pipe resonator, with emphasis on significant differences between the two situations.