A periodic structuration of matter induces band foldings and thus band gaps
M.S. Kushvaha et al. , Phys. Rev. Lett. 71 , 2022 (1993) First complete phononic band gap: aluminum cylinders in nickel In comparison to photonic crystals, contrasts between elastic material constants can be quite strong
Sound shield: a centimeter-size arrangement stops audible sound!
Z.Y. Liu et al. , Science 289 , 1735 (2000) A “soft” silicone coating over a rigid lead sphere creates localized modes (Fano resonances). Wavelength = 85 cm @ 400 MHz Silicone L ongitudinal velocity = 23 m/s Shear velocity = 5.5 m/s