Interaction of pipe tone and edge tone in organ pipe oscillation
A. W. Nolle · The Journal of the Acoustical Society of America · 2003
Inharmonic partials in an organ pipe tone can occur in clusters, at uniform frequency separation. The primary object of this discussion is to demonstrate that these clusters arise in a nonlinear process: Edge tone oscillation is modulated at the fundamental frequency of the pipe tone. The mechanism is demonstrated by a laboratory analog, in which periodic deflection of a jet producing an edge tone is forced by a transverse acoustic flow, and also by a numerical analog. Additional examples show that the simultaneous occurrence of a pipe tone and an unmodulated edge tone can occur at low amplitudes of oscillation, where the nonlinear interaction is unimportant.