Shaping reverberating sound fields with an actively tunable metasurface

Significance

Wavefront shaping with spatial light modulators has recently motivated many studies in the field of light manipulation in diffusive media. Here, we extend this concept to acoustic waves by designing and building a binary phase-modulating spatial sound modulator (SSM). The SSM is an acoustic metasurface consisting of unit cells with two states, switchable through programmed electronics. We demonstrate in audible frequencies, and in a reverberating environment, the capability of controlling and reshaping any complex sound field. Our work will not only open avenues to study wave propagation in complex and chaotic media but also inspire applications in acoustic engineering.

Abstract

A reverberating environment is a common complex medium for airborne sound, with familiar examples such as music halls and lecture theaters. The complexity of reverberating sound fields has hindered their meaningful control. Here, by combining acoustic metasurface and adaptive wavefield shaping, we demonstrate the versatile control of reverberating sound fields in a room. This is achieved through the design and the realization of a binary phase-modulating spatial sound modulator that is based on an actively reconfigurable acoustic metasurface. We demonstrate useful functionalities including the creation of quiet zones and hotspots in a typical reverberating environment.