  The theory of acoustic wave scattering by many small bodies is developed for
bodies with impedance boundary condition. It is shown that if one embeds many
small particles in a bounded domain, filled with a known material, then one can
create a new material with the properties very different from the properties of
the original material. Moreover, these very different properties occur although
the total volume of the embedded small particles is negligible compared with
the volume of the original material.
