Acoustic analysis of a metasurface for normal and random incidence sound waves

Abstract

This article proposes an acoustic metasurface (AMS) capable of effectively absorbing sound frequencies in the range of 100−800 Hz. The input and airborne impedances are combined considering incident normal and oblique sound waves, and the sound absorption capacity is presented analytically and numerically. Results of 99% sound absorption under normal incidence are obtained experimentally. Considering the radiation impedance of the Thomasson and Paris' models the analytical study of the sound absorption of different samples of the absorber in diffuse field is discussed. The results are coherent and confirm the influence of the sample area on its acoustic performance. This approach provides a practical and reliable procedure for evaluating the behavior of the AMS in a reverberant sound field.