Acoustics: Sound Fields, Transducers and Vibration, 2nd Edition

4.24. Finite lossy tubes

A two-port network for a finite tube of any length [13]

We have already introduced two-port networks for transducers using z-parameters in Section 3.10. Here we shall apply the theory to a tube with viscous and thermal losses. A general equivalent circuit for passive two-port networks is shown in Fig. 4.43. Because of the reciprocity of the tube, or in other words, the fact that it does not matter at which end there is a transmitter or receiver, we obtain z ₂₂   =   z ₁₁ and z ₂₁   =   z ₁₂.

Figure 4.43 Equivalent electrical circuit for a general passive 2-port network.

From Eq. (3.64), we write