Acoustic Metacages for Omnidirectional Sound Shielding

TL;DR

This paper introduces a novel two-dimensional acoustic metacage that effectively shields sound from all directions while allowing fluid flow, using gradient-index metasurfaces with open channels and Helmholtz resonators, verified by simulations and experiments.

Contribution

The paper presents a new design of an acoustic metacage that achieves omnidirectional sound shielding with subwavelength thickness and fluid permeability, combining metasurface engineering with resonator integration.

Findings

Effective omnidirectional sound shielding demonstrated

Low sound transmission confirmed by simulations and experiments

Design allows steady fluid flow alongside sound insulation

Abstract

Conventional sound shielding structures typically prevent fluid transport between the exterior and interior. A design of a two-dimensional acoustic metacage with subwavelength thickness which can shield acoustic waves from all directions while allowing steady fluid flow is presented in this paper. The structure is designed based on acoustic gradient-index metasurfaces composed of open channels and shunted Helmholtz resonators. The strong parallel momentum on the metacage surface rejects in-plane sound at an arbitrary angle of incidence which leads to low sound transmission through the metacage. The performance of the proposed metacage is verified by numerical simulations and measurements on a three-dimensional printed prototype. The acoustic metacage has potential applications in sound insulation where steady fluid flow is necessary or advantageous.