Harmonic generation meehanism in organ pipes

Abstract

A whole view on the harmonic generation in organ pipes is presented. It consists of elementary processes: (a) excitory source spectrum generation by the jet, (b) filtration by the inharmonic normal modes of the passive system, and (c) radiation from the pipe ends. Lateral jet velocity distribution is responsible for the source spectrum. Filtration and radiation emphasize the resultant source spectrum. Harmonic generation mechanism is classified into the unsaturated and saturated regimes, and formulated on the basis of current- and pressure-drive models. Theoretical consideration deduced: (1) Contribution of the pressure-drive to the harmonic generation is not significant. (2) Harmonic structure and its development in the unsaturated regime are defined by the matrix of the jet offset and the vector of the jet deflection amplitude. (3) A decisive factor determining the harmonic structure in the fully saturated regime is the time interval ratio of the jet switching action. © 1984, Acoustical Society of Japan. All rights reserved.