Acoustic metamaterials

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Acoustic metamaterials are artificially fabricated materials designed to control, direct, and manipulate sound in the form of sonic, infrasonic, or ultrasonic waves, as these might occur in gases, liquids, and solids. The hereditary line into acoustic metamaterials follows from theory and research in electromagnetic metamaterials. Furthermore, with acoustic metamaterials, sonic waves can now be extended to the negative refraction domain. Control of the various forms of sound waves is mostly accomplished through the bulk modulus , mass density, and chirality. The bulk modulus and density are counterparts of the intrinsic parameters, permittivity and permeability, in electromagnetic metamaterials. Related to this is the mechanics of wave propagation in a lattice structure. Also materials have mass, and instrinsic degrees of stiffness. Together, these form a resonant system, and the mechanical resonance may be excited by appropriate sonic frequencies.