Use the Interior Impedance or Pair Impedance node in a frequency domain analysis to define the specific transfer impedance at the boundary between two domains or parts in an assembly as the ratio of pressure drop to normal velocity Zn = Δp/(n · u). The formulation is following the so-called Ingard-Myers condition. The associated boundary condition is

Enter a Specific transfer impedance Zn (SI unit: Pa·s/m).