Patent ID: 7639830

Claim:
An apparatus for acoustic loading of a diaphragm having a voice coil with a circumference defined by a first diameter affixed on a non-compression side, the voice coil's circumference being smaller than the diaphragm's outer circumference, the apparatus comprising: a rear face having a shape corresponding to a shape of a compression side of the diaphragm; a front face opposite to said rear face along an axis of symmetry; and a plurality of voids formed between said rear face and said front face, wherein said plurality of voids intersects said rear face as a plurality of inlets, said plurality of inlets having a first total cross-section area defining a first compression ratio in a proximity of the first diameter, and a second total cross-section area defining a second compression ratio in at least a portion of the remaining area of said rear face, wherein the first compression ratio is greater than the second compression ratio.