Tone Production in the Organ Flue Pipe
Derwent M. A. Mercer · The Journal of the Acoustical Society of America · 1955
A number of measurements have been made of middle C open diapason organ pipes during variation of the voicing adjustments. The effect on the spectrum and on the initial transient of alterations in height of mouth, languid setting, and wind pressure are presented. The effect of nicking is shown to be a decrease in the random noise background. Theories of action of the flue pipe are reviewed. Measurements on pipes with bodies removed show that the natural edge-tone frequencies of the flue/upper lip combination coincide with the whistles and other noises given by pipes before they come to full speech, but the edge-tone appears to have no part in the mature speech of the pipe. A mechanism of operation similar to the older “air-reed” theories, which explains the basic phenomena and also many facts empirically known to pipe-voicers, is presented and discussed.