Patent ID: 7207413

Claim:
An apparatus for improving the acoustic impedance for a loudspeaker comprising: a first enclosure with six walls connected to define a first box structure, surfaces of three of the walls being a first wave-guide; a second enclosure disposed within said first enclosure, the second enclosure having at least three walls attached to a front wall of the first enclosure to define a second box structure with an enclosed compartment between the first box structure and the seconded box structure, surfaces of three of the walls of the second enclosure being a second wave-guide; a termination member affixed at ends of the first and second wave-guides having a surface being a third wave-guide; an aperture located in a wall of the second enclosure detaining a single opening into the enclosed compartment; an alternative density transmission medium covering a majority of at least one of said wave-guides; at least one opening in the front wall common to the first enclosure and the second enclosure, hereinafter called a baffle board, to mount a bi-directional loudspeaker; and a bi-directional loudspeaker mounted on the baffle board; wherein: the first, second and third wave-guide comprise an embedded acoustic transmission line; and the interaction of a sound wave with the alternative density transmission medium improves the acoustic impedance of the apparatus.