Actually, this does not seem to happen, at least not as much as suggested by Olney. In fact, in the empty line impulse response, we have no peak at 2.75 ms to anticipate the slower acoustic wave traveling inside the foam. One could assume that the wave is deformed to the point where it starts to move in a partially incident way inside the tube, so as to cross both portions of the line, but this is pure speculation. The interesting thing to note is that, even in this case, once the principles of analogies are correctly applied, the model generates a simulation that predicts the measurements in a satisfactory way.