  Phononic crystals and acoustic metamaterials are architected lattices
designed to control the propagation of acoustic or elastic waves. In these
materials, the dispersion properties and the energy transfer are controlled by
selecting the lattices' geometry and their constitutive material properties.
Most designs, however, only affect one mode of energy propagation, transmitted
either as acoustic, airborne sound or as elastic, structural vibrations. Here,
we present a design methodology to attenuate both acoustic and elastic waves
simultaneously in all polarizations. We experimentally realize the first
three-dimensional, load bearing, architected lattice, composed of a
single-material, that responds in a broadband frequency range in all
directions.
