Synchronization of organ pipes by means of air flow coupling: experimental observations and modeling
Mathieu Abel, Reimund Gerhard, Steffen Bergweiler · 2005
We report measurements on two organ pipes positioned side by side. We investigate two different questions. First, the mutual influence of two pipes with different pitch. In analogy to the coupling of two nonlinear oscillators with feedback, one observes a frequency locking, which can be explained by synchronization theory. Second, we measure the dependence of the frequency of the signals emitted by two mutually detuned pipes with varying distance between the pipes. The spectrum shows a broad ``hump'' structure, not found for coupled oscillators. This indicates a complicated hydrodynamical coupling of the two jets creating the acoustic field when exiting from the pipe mouth. We interpret our acoustic measurements with a model for the flow which exits from the flues of the pipes.