Fig. 5: The meta-barrier structures are constructed through a two-dimensional periodic distribution of Helmholtz resonator unit cells.

a The unit cell consists of a Helmholtz cavity with two openings and a central airflow vent, along with the transmission loss spectrum of the meta-barrier. Reproduced with permission from ref. ¹¹⁴. b The meta-barrier and the multi-layer helical supercell, along with the power transmission spectrum. Reproduced with permission from ref. ⁵⁴. c The reconfigurable origami acoustic meta-barrier, as well as the variation of ventilation and average transmission loss with the opening angle \(\theta\). Reproduced with permission from ref. ⁶⁵.