Giant acoustic concentration by extraordinary transmission in zero-mass metamaterials

Phys Rev Lett. 2013 Jun 14;110(24):244302. doi: 10.1103/PhysRevLett.110.244302. Epub 2013 Jun 13.


We demonstrate 97%, 89%, and 76% transmission of sound amplitude in air through walls perforated with subwavelength holes of areal coverage fractions 0.10, 0.03, and 0.01, respectively, producing 94-, 950-, and 5700-fold intensity enhancements therein. This remarkable level of extraordinary acoustic transmission is achieved with thin tensioned circular membranes, making the mass of the air in the holes effectively vanish. Imaging the pressure field confirms incident-angle independent transmission, thus realizing a bona fide invisible wall. Applications include high-resolution acoustic sensing.