Control of the stop band of an acoustic double fishnet

The acoustic transmittance of two closely spaced solid plates, each perforated with a square array of cylindrical holes, exhibits a band of near-perfect acoustic attenuation originating from hybridization between a resonance in the gap separating the plates and pipe resonances in the holes. Displacement of one plate relative to the other, such that the holes are no longer aligned, or an increase in the plate separation leads to an increased center frequency of the stop band. This ability to easily tune the frequency of the stop band may prove advantageous.