The influence of curvature on the vibration and tone quality of pipe organ reed tongues

Given certain design constraints, such as the type of stop being voiced and the desired tone quality, organ reed voicers must curve each tongue so as to produce the best and most stable tone, as well as maintaining a consistent tone quality across an entire rank of pipes. This study investigated the effects of varying tongue curvatures on two pipes, an F2 Trompette and an F2 Clarinet. Reed vibration was measured under typical conditions by laser vibrometer; the pressure waves in the boot and shallot were measured by means of one-eighth inch microphones and the emitted sound was recorded at the egress. By integrating the velocity data, the displacement of the reed may be plotted in tandem with the pressure difference across the reed, allowing tongue position to be plotted versus the pressure variation during one steady-state cycle for each reed while vibrating. These graphs can then be compared and correlated to the observed tone quality for each of the differently curved reeds.