An analysis of the spatio-spectral acoustic filtering effect of sonic crystals

This study numerically investigates the spatio-spectral sound transmission properties of a sonic crystal flat lens and presents a discussion on the effects of negative refraction on the spatio-spectral selectivity of sonic crystals. For this propose, pulse response analyses are carried out to demonstrate the spatio-spectral acoustic transmission features of a triangular lattice two-dimensional sonic crystal flat lens at the bottom edge of the second frequency band. The spectral analysis indicates the existence of a spatial filtering effect resulting from the wave focalization of the negative refracted wave beams emitted from a point source. We theoretically demonstrate that this effect can be utilized in the implementation of highly frequency-selective spatial sound filters by using sonic crystal flat lenses from point type acoustic sources.