Effect of Wall Material on Organ-Pipe Tone—An Evaluation of Some Earlier Experiments

Abstract

Dayton C. Miller has described experiments on a double-wall organ pipe of rectangular cross section in which the space between the wails could be filled with water, producing substantial alterations in pitch and tone [Science 29, 161 (1909)]. These experiments have been quoted by Miller and others as demonstrating the influence of the wall material on the tone quality of woodwind instruments. Calculations of the elastic deformations to be expected under internal pressure show that Miller's results are due to the rectangular cross section of his pipe and would be absent for one of circular cross section. This result was verified in this laboratory by constructing a double-wall cylindrical organ pipe, for which no measurable changes in tone were produced when the space between the walls was filled with water. This result is also verified by the experiments of Boner and Newman on cylindrical organ pipes [J. Acoust. Soc. Am. 12, 83 (1940)]. The small differences in pitch and quality among the thinner pipes noted by these authors can be explained by assuming the pipes to have a slightly elliptical cross section. For cylindrical organ pipes of reasonable wall rigidity, the steady-state tone quality should not depend on the wall material.