Figure 7
From: Ultrathin acoustic metamaterial as super absorber for broadband low-frequency underwater sound
(a–c) Broadband sound absorption of the ultrathin acoustic metamaterial with eight parallel hybrid units. Each hybrid unit is composed of a metamaterial unit with higher height and a metamaterial unit with lower height. A division plate is set to separate the two units. The blue line and circles represent the sound absorption coefficient from theoretical predictions and FE simulation results, respectively. (d) The normalized surface acoustic resistance (red) and acoustic reactance (blue) of the ultra-broadband sound absorber.
