Patent attributes
A membrane-type acoustic absorber structure is provided for an acoustic panel. The absorber structure includes an acoustic substrate. A plurality of spaced apart unit cells are provided in the acoustic substrate and arranged in a periodic array. Each unit cell includes at least one perimeter boundary wall and a bottom wall portion. The perimeter boundary wall and bottom wall portion cooperate to define a chamber with an opening and a chamber cavity having a chamber volume. An elastic membrane is disposed at the chamber opening and configured for sealing the chamber cavity. At least one lossy porous medium is provided aligned with, and separated a distance from, the elastic membrane. A fluid/gas is provided in the chamber volume. In certain aspects, the unit cells may have identical dimensions, having the same resonance frequency. In other aspects, the unit cells may have different dimensions, providing a broadband absorber.
