Patent ID: 8413761

Claim:
A precursor acoustic structure comprising: a honeycomb comprising a first edge and a second edge, said honeycomb further comprising a plurality of walls that extend between said first and second edges, said walls defining a plurality of cells wherein each of said cells has a cross-sectional area measured perpendicular to said walls and a depth defined by the distance between said first and second edges; a septum cap that is held in place within at least one of said cells only by friction locking of said septum cap to said walls, said septum cap comprising a sheet of flexible material that has a thickness and a perimeter, said sheet of flexible material being sufficiently flexible to be folded and inserted into said cell to form said septum cap comprising a perforated resonator portion that extends in the same plane transversely across said cell and which has an outer edge located at said walls and a flange portion that extends between the outer edge of said perforated resonator portion and the perimeter of said sheet of flexible material, said flange portion extending parallel to said walls and comprising an anchoring surface which is in frictional contact with said walls, said anchoring surface having a width wherein the width of said anchoring surface and the bounce-back of said flexible material is sufficient to provide friction locking of said septum cap to said cell walls.