of homogenization based on the scattering properties of the cluster. Exact formulas for the effective parameters i.e., effective sound speed and effective density are obtained as a function of the location of each cylinder and the physical parameters density and speed of sound of cylinders and the embedded medium. Results for several fluid-fluid composite systems are reported. The case of rigid infinite density cylinders in air is deeply analyzed, showing results for ordered and disordered lattices. It is concluded that the method provides a tool of designing acoustic metamaterials with prefixed refractive properties.