Reconfigurable piezoelectric metamaterial for selective noise directivity

This work explores strategies to change the directivity of sound radiated from an oscillating metamaterial plate. To this end, the vibro-acoustic behavior of a plate that hosts an array of piezoelectric unit cells, whose inductive shunt resonance frequencies can assume different predefined configurations in space, is numerically investigated. The effects of such configurations on (i) the structural normal velocity of the plate, (ii) the hemispherical acoustic field estimated based on Rayleigh's integral, and (iii) the non -negative acoustic intensity are discussed. The numerical results show that simple changes in the unit cell's tuning configuration in space can reduce, totally attenuate, or enhance the sound radiated in specific directions, findings that may pave the way to the use of reconfigurable metamaterials as effective systems for selective radiated noise directivity.