Tunable acoustic scattering from a spatiotemporally modulated flat metasurface

Spatiotemporal modulation (STM) has recently been used to improve diffusion from finite apertures of conventional acoustic diffuser profiles by introducing STM of the termination impedance of the diffuser wells and to scatter acoustic energy at frequencies that are up- and down-shifted from the incident wave frequency by integer multiples of the modulation frequencies. The present work employs a semi-analytical model of acoustic scattering from an STM acoustic metasurface to investigate the tunability of scattering from a flat metasurface with STM admittance by demonstrating nonreciprocal and diffuse scattering of sound via a parametric study on the modulation frequency and admittance amplitude. The results provide insight into the use of STM of input admittance to control acoustic scattering from acoustic metasurfaces.