acoustic metamaterial for insulation and process for its manufacture

The present invention is in the field of acoustic attenuation devices made from acoustic metamaterial and relates to a porous acoustic resonator ball, characterized in that the Young's modulus of the material of said resonator is less than 1 GPa, porosity said resonator is between 20% and 50%, the majority of the pores of said resonator is filled with a gas, and the majority of said pores is interconnected via at least one pore with the outside of said resonator.