Drawer-like tunable ventilated sound barriera)

Ventilated acoustic barriers have great potential for practical applications; however, most of the current designs are limited by bandwidth and adjustability. Here, this study experimentally demonstrates a drawer-like tunable ventilated sound barrier with low-frequency bandwidth optimization, which is a monolayer periodic lattice of a pair of oppositely oriented Helmholtz resonators with drawer-like movable design. The sound insulation arises from sound reflection and absorption caused by the coupling of symmetric and anti-symmetric modes. The drawer-like movable design allows precise control of the resonant frequency of the unit cell and the working bandwidth of the ventilated barrier. Furthermore, this study has optimized two types of dual-layer unit cells composed of two and four pairs of oppositely oriented Helmholtz resonators, where the fractional bandwidths (the ratio of the bandwidth to the center frequency) of sound insulation have reached about 14.8% and 31.8%, respectively. The drawer-like tunable ventilated barriers have the advantages of tunable and optimizable bandwidth for low-frequency sound insulation, opening a practical route towards architectural acoustics and ventilated noise reduction.