Patent ID: 6896096

Claim:
An acoustic structure comprising: a first, rigid panel, a second, rigid panel aligned in spaced, substantially parallel, relationship with the first panel, a multiplicity of partition walls running transverse to the plan s of the panels and dividing the interior space of the acoustic structure into a single layer of cells bounded at one face by the inside of the first panel and bounded at the opposite face by the inside of the second panel, the partition walls being bonded at the one face to the inside of the first panel and at the opposite ace to the inside of the second panel, and a multiplicity of apertures in the partition walls providing communication between adjacent cells of the single layer of cells, and in which: the cells each have a cross-sectional area parallel to the panels in the range 0.25 to 10 cm 2 , the apertures each have a cross-sectional area of at least 0.04 cm 2 , and at least 55% of the wall between a cell and an adjoining cell is imperforate.