Perfect absorption in mirror-symmetric acoustic metascreens

TL;DR

This paper introduces mirror-symmetric acoustic metascreens capable of achieving perfect sound absorption from both sides, through degenerate resonances, supported by theoretical modeling and experimental validation.

Contribution

The work presents a novel design of symmetric metascreens with degenerate resonances enabling perfect absorption, supported by a hybrid analytical model and experimental verification.

Findings

Achieved perfect sound absorption from both sides of the metascreen.

Validated theoretical predictions with experimental results.

Demonstrated potential for ventilation noise control applications.

Abstract

Mirror-symmetric acoustic metascreens producing perfect absorption independently of the incidence side are theoretically and experimentally reported in this work. The mirror-symmetric resonant building blocks of the metascreen support symmetric and antisymmetric resonances that can be tuned to be at the same frequency (degenerate resonances). The geometry of the building blocks is optimized to critically couple both the symmetric and the antisymmetric resonances at the same frequency allowing perfect absorption of sound from both sides of the metascreen. A hybrid analytical model based on the transfer matrix method and the modal decomposition of the exterior acoustic field is developed to analyze the scattering properties of the metascreen. The resulting geometry is 3D printed and experimentally tested in an impedance tube. Experimental results agree well with the theoretical predictions proving the efficiency of these metascreens for the perfect absorption of sound in the ventilation problems.