Extensive tailorability of sound absorption using acoustic metamaterials

We present an experimental demonstration of sound absorption tailorability, using acoustic metamaterials made of resonant cavities that take advantage of the inherent visco-thermal characteristics of air. As confirmed by numerical calculation, we particularly show that using quarter-wave-like resonators made of deep subwavelength slits allows a high confinement of the acoustic energy of an incident wave. This leads to enhance the dissipation in the cavities and, consequently, generates strong sound absorption, even over a wide frequency band. This paves the way for tremendous opportunities in acoustic comfort because of their potentially low density, low volume, broadband, and tailorable capabilities.