Full manipulation of sound scattering via piezoelectric reconfigurable acoustic metamaterials

Herein, we propose a type of dual-layered piezoelectric acoustic metamaterial (D-PAM) integrating mechanical and electrical components for sound scattering manipulation. The D-PAM is a double-sided structure that comprises two identical piezoelectric acoustic metamaterials (PAMs) fixed at the outer boundaries and a sealed air cavity sandwiched in the middle. In the D-PAM, each layer of the piezoelectric acoustic metamaterial consists of a membrane-type oscillator and a piezoelectric patch connected to a shunt circuit. Since the acoustic impedance of each layer of the piezoelectric acoustic metamaterial can be adjusted by independently regulating the corresponding shunt circuit, the D-PAM is capable of precisely controlling sound reflection, sound transmission, and sound absorption. An analytical scattering model of the D-PAM is developed to reveal the adjustable range and the coupling relationship between the reflection and transmission coefficients. In addition, the influence of piezoelectric shunt circuits on sound scattering is analyzed by combining the scattering model and the electroacoustic model. Finally, experimental validation performed in an acoustic impedance tube confirms the effectiveness of the proposed D-PAM in customizable manipulation of the full sound scattering characteristics. Our work may enable promising applications in noise control, mechanical computation, and acoustic imaging.