Bulk and surface acoustic waves in double negative metamaterial

Propagating of the acoustic wave in quasi-isotropic metamaterial is considered. The composite is consisted of an isotropic background material and embedded resonators in it. The frequency of the wave is taken that the wavelength is much longer that size of inclusions and distance between them. Dispersion of effective stiffness and density is calculated by coherent potential approximation. Zones where parameters reach negative values are estimated. Dispersion for the surface acoustic wave at the interface between metamaterial and ¿normal¿ matrial is calculated.