Acoustic metacage with arbitrary shape for broadband and ventilated sound insulation.

Here, we experimentally demonstrate a novel strategy for broadband acoustic insulation of an arbitrary shaped region by arranging a localized rainbow trapped metastructure at a deep subwavelength scale. The metastructure constitutes radial gradient grooves along the azimuth direction and can help realize localized acoustic rainbow trapping. We show that such metastructures can be used to construct a region with arbitrary geometry for sound insulation and keep high ventilation simultaneously, thus, denoted as an acoustic metacage. Based on the numerical simulations and experimental observations, the results indicate that the broadband soundproof effect of the metacage is robust against the location of the acoustic source. Finally, we discuss the relationship between the soundproof efficiency and the ventilated ratio of the metacage and find that the ventilation window can still achieve a rate of 55% when the transmittance loss is above 10 dB. The proposed acoustic metacage could open up an avenue for realizing broadband sound insulation with high ventilation and an arbitrary shaped area. [ABSTRACT FROM AUTHOR]