Sustainable acoustic metasurfaces for sound control

Sound attenuation with conventional acoustic materials is subject to the mass law andrequires massive and bulky structures at low frequencies. A possible alternative solution is providedby the use of metamaterials, which are artificial materials properly engineered to obtain propertiesand characteristics that it is not possible to find in natural materials. Theory and applications ofmetamaterials, already consolidated in electromagnetism, can be extended to acoustics; in particular,they can be applied to improve the properties of acoustical panels. The design of acoustic metasurfacesthat could effectively control transmitted sound in unconventional ways appears a significantsubject to be investigated, given its wide-ranging possible applications. In this contribution, weinvestigate the application of a metasurface-inspired technique to achieve the acoustical insulationof an environment. The designed surface has subwavelength thickness and structuring and couldbe realized with cheap, lightweight and sustainable materials. We present a few examples of suchstructures and analyze their acoustical behavior by means of full-wave simulations.