Locally resonant sonic materials

We have fabricated sonic crystals, based on the idea of Localized resonant structures, that exhibit spectral gaps with a Lattice constant two orders of magnitude smaller than the relevant wavelength. Disordered composites made from such localized resonant structures behave as a material with effective negative elastic constants and a total wave reflector within certain tunable sonic frequency ranges. A 2-centimeter slab of this composite material is shown to break the conventional mass-density Law of sound transmission by one or more orders of magnitude at 400 hertz.