Figure 3

Comparison of sound absorption in three different metasurfaces. (a) Calculated sound absorption spectra for a bilayer metasurface with \(\beta _{1}=0.161\), \(\beta _{2}=0\) and \(d=0\) (black line), a bilayer metasurface with \(\beta _{1}=\beta _{2}=0.148\) and \(d=0\) (red line), and a single-layer metasurface with \(\beta _{1}=0.108\) (blue line). All the metasurfaces have an open area ratio \(p_{o}=0.5\). The absorption approaches a maximum \(A_{R}\) at resonant frequency \(f_{R}\). (b) \(A_{R}\) as a function of \(\beta _{1}\) for the three metasurfaces.