Ultrabroadband Acoustic Ventilation Barriers via Hybrid-Functional Metasurfaces

Ventilation barriers allowing simultaneous sound blocking and free airflow passage are of great challenge but necessary for particular scenarios calling sound-proofing ventilation. Previous works based on local resonance or Fano-like interference serve a narrow working range around the resonant destructive-interference frequency. Efforts made broadband designs show limited bandwidth typically smaller than half an octave. Here, we theoretically design ultra-broadband ventilation barrier via hybridizing dissipation interference. Confirmed by experiments, synergistic effect from our hybrid-functional metasurface significantly expand scope its frequencies, leading to effective more 90% incident energy in 650-2000 Hz, while structural thickness is only 53 mm $(\sim \lambda / 10)$. Our shows flexibility customizing capable handling coming various directions, which has potential air-permeable yet applications.