(a) Tunable broadband reflective acoustic metasurface [55]. (b) Highly efficient acoustic metagrating with strongly coupled surface grooves [62]. (c) Helix structure for low frequency acoustic energy harvesting [64]. (d) A sonic band gap based on the locally resonant phononic plates with stubs [69,71]. (e) Vibration band gaps in double-vibrator pillared PnCs plate [80]. (f) Laminated plate-type acoustic metamaterials with Willis coupling effects for broadband low-frequency sound insulation [74]. (g) Broadband asymmetric propagation in pillared meta-plates [78].