Each junction reflects by k = (A[i]-A[i+1]) / (A[i]+A[i+1]), area ∝ diameter². One-multiply scattering: w = k*(R - L), then R→R+w, L→L+w. Reflections are smoothed per block for click-free reshaping. Swap the Rosenberg source for a reed/lip excitation and it becomes a wind-bore model.