If we couldn’t flow futuristic would you…? Breaking the accepted mass-density law of sound, dub-style black outs with bass shielding on a negative elastic tip. This is sonik tek. Get ready to lie down: ninforush coming on.Periodic modulations in sound velocity can be used to shield sound within a certain frequency range in a manner analogous to the blocking of light by photonic band gap materials. However, the spatial modulation must be of the same order of magnitude as the sonic wavelength, which would make such structures impracticably large. Or so you thought.Zhengyou Liu and his crew [ Xixiang Zhang, Yiwei Mao, Y. Y. Zhu, Zhiyu Yang, C. T. Chan, Ping Sheng], have shown that composites with locally resonant structural units can shield sound with lattice units two orders of magnitude smaller than the relevant sonic wavelength. By varying the size and geometry of the structural units, frequency ranges over which the material acts as a sonic shield can be varied. Thus, relatively thin layers of material can be used as selective sound shields. As Zhengyou Liu explained:“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.”