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

7.18. Two-port network for a bass-reflex enclosure

A sketch of the two-port enclosure is shown in Fig. 7.34. It is a generic enclosure, which we shall use for purposes other than the bass-reflex enclosure in Example 7.3, such as the simple enclosure in Section 7.6, normal modes of a rectangular enclosure in Section 10.3, and horn bends in Section 9.14.

The two ports, represented by piston 1 and piston 2, are circular and planar. To simplify the problem, there is only acoustic lining on the surface opposite to the two ports, represented by a termination impedance at z   =   0. For a bass-reflex enclosure, this avoids having too much absorption which would negate the advantage of the port, the resonance of which is best damped by the acousto-mechano-electrical ...