Ultra-thin metasurface meta-barrier for integrated ventilation and sound insulation

Traditional ventilation meta-barrier is deficient in isolating low-frequency noise. To solve the problems of insufficient low-frequency sound insulation performance, narrow frequency band, large structural thickness, and contradiction between ventilation performance and sound insulation performance of traditional ventilation meta-barrier, this paper proposes an ultra-thin space-shift metasurface meta-barrier that achieves excellent broadband sound insulation performance while maintaining a thickness as low as approximately 20 mm and ensuring high ventilation efficiency. The non-ventilated regions of the meta-barrier are equipped with folded labyrinthine resonant sound-absorbing units of gradient lengths, which generate broadband continuous absorption peaks. By using absorption instead of insulation, the meta-barrier achieves broadband sound attenuation. The sound-absorbing unit has a certain absorption radius, it covers the ventilated areas. It absorbs the surrounding sound energy, and dissipates it by overcoming the resistance friction. Therefore, it can overcome the problem of sound leakage caused by strong sound wave diffraction and effectively isolate the sound while maintaining ventilation. The ventilation area ratio reaches 25%, with an average sound insulation of 14 dB within a wide frequency range of 900-2000 Hz. The proposed meta-barrier structure has a thinner thickness, larger ventilation area, and wider working band, which demonstrates its wide engineering application value.