The separation distance of two equally tuned, aeroacoustically coupled organ pipes is varied stepwise in a synchronization experiment. At distances of multiples of about half the wavelength of the fundamentals, abrupt changes of SPL and fundamental frequency of the coupled and synchronized system can be observed. Frequency jumps also occur at higher harmonics. The nonlinear coupling function of the system implicitly takes into account the time delay of the system caused by the separation distance and therefore plays an important role for the observed phenomenon. The effect can be explained as a switch of synchronization states from in-phase to anti-phase and vice versa.