Patent attributes
A sparse acoustic absorber includes a periodic array of spaced apart unit cells, generally having a lateral fill factor less than 0.5. Each unit cell includes a pair of joined, and inverted, Helmholtz resonators, having neck portions that point in opposite directions. This structure enables ambient fluid, such as air, to pass through the absorber. The absorber predominantly absorbs acoustic waves having a resonant frequency when such waves are incident on the absorber in one direction, and predominantly reflect such waves when they are incident on the absorber in the opposite direction. Dual-function sound suppression systems incorporate such an absorber into a porous substrate, such as a wire mesh, that enables fluid to pass and alternatively absorbs or reflects sound.
