Patent ID: 8459407

Claim:
A system, comprising: a sound-attenuating device, comprising: a hollow wall having a sound-attenuating cavity; a sound-attenuating material disposed in the sound-attenuating cavity of the hollow wall; and a plurality of openings into the hollow wall, wherein the openings are disposed adjacent projections that enable entry of sound waves into the hollow wall and substantially block departure of the sound waves away from the hollow wall, and the projections comprise inwardly tapered projections that extend inwardly from the hollow wall into the sound-attenuating cavity, wherein the inwardly tapered projections completely overlap the openings to block a straight path through the openings, wherein the hollow wall comprises first and second perforated walls that oppose one another about the sound-attenuating material disposed in the sound-attenuating cavity, the first perforated wall comprises a first plurality of openings with a first plurality of inwardly tapered projections that extend inwardly from the first perforated wall into the sound-attenuating cavity, and the second perforated wall comprises a second plurality of openings with a second plurality of inwardly tapered projections that extend inwardly from the second perforated wall into the sound-attenuating cavity, wherein the first plurality of inwardly tapered projections each comprise a first section angled inwardly with respect to a second section about a first vertex, the second plurality of inwardly tapered projections each comprise a third section angled inwardly with respect to a fourth section about a second vertex disposed across the first vertex to direct the sound waves into the sound-attenuating material and bounce the sound waves back and forth between the first and second perforated walls.