The high-efficiency and broadband acoustic reduction performance in a miniaturized free-flow structure remains challenging in acoustic engineering applications due to the contradiction of ventilation and acoustic reduction performance. Traditional acoustic absorbers can sufficiently attenuate acoustic wave, but meanwhile, block fluid flow due to the longitudinal nature of acoustic waves that can transmit among any small holes. Although different types of ventilated metamaterial absorbers (VMAs) with proper reduction and ventilation performance have been demonstrated recently, their insufficiencies lie in small open-area ratios, not efficient-enough reduction performance, bulky structure, and narrow working band. To further solve existing defects, a ventilated broadband absorber with the miniaturized metamaterial structure has been proposed.Thedesigned absorber consists of miniaturized Archimedean spiral units, which can be easily stacked to achieve broadband and ventilated performance. This work opens up possibilities for practical acoustic applications where both noise control and ventilation are required, especially in a small space.
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