On the mechanism of sound production in organ pipes

It is shown that both the Cremer‐Ising and Coltman mechanisms for sound production in organ pipes are comprehended by a more general approach, based on conservation of linear momentum. By calculating force per unit area exerted by the jet on a control volume containing the mixing region, and equating this to the difference in pressure along the pipe axis, it is possible to derive an expression for acoustic particle velocity in the standing wave as a function of the jet driving flow spectrum. The momentum model of the jet‐pipe interaction is able to explain the Coltman radiation symmetry effect, and also accounts for the role of entrained air in sound production. Additional spectral interaction terms, not previously noted, are found to play a significant role in the production of sound‐pressure fluctuations in the pipe. The fluctuating lift force at the edge is found to contribute to the sustenance of the pipe‐cavity oscillation below resonance, opposing it above resonance. In the near vicinity of the reso...