3D Acoustic Metamaterial Using Interconnected Helmholtz Resonators

Helmholtz resonators distributed in an array are one way to create an acoustic metamaterial for air-borne sound, ideally achieving perfect absorption at the resonance frequency. While a large number of variations have been reported in literature, the individual resonators are typically stand-alone elements. In this contribution we investigate the placement of interconnected Helmholtz resonators in a three-dimensional lattice, where multiple necks connect adjacent cavities. We have studied such lattices using finite element analysis, fabricated selected design with 3D-printing, and experimentally validated results in impedance tube measurements. This work is based on our prior research in 3D metamaterials for vibrations and elastic waves, which has demonstrated very strong damping inside ultra-wide band gaps. Likewise, we aim to achieve wide frequency ranges of strong sound absorption and high transmission loss greater than equivalent 2D arrangements.