Sound insulation via a reconfigurable ventilation barrier with ultra-thin zigzag structures.

Acoustic ventilation barriers (AVBs) constructed from metamaterials can effectively insulate sound waves while maintaining airflow, but previous schemes suffer from complex geometric structures. Here, we propose a reconfigurable AVB with subwavelength thickness (0.15λ), which is composed of simple zigzag structures with regular intervals and can be assembled into a full enclosure with an arbitrary shape. It is the interaction between the scattered wave of the zigzag structure and the un-scattered wave through the air channel that leads to a transmission dip and hence a sound insulation. Numerical simulations and experimental demonstrations consistently verify that the AVB possesses excellent omnidirectional sound insulation, while the width of the air channel can reach three times the unit width. As the number of cavity increases, the acoustic insulation bandwidth is broadened from 0.875/λ to 2.75/λ. As an example, a circle AVB is further demonstrated to shield acoustic waves emitting from either the interior or exterior. Experimental measurements indicate that the average sound transmission losses can reach roughly 19 dB and 15 dB, respectively. We believe that the proposed AVB may find potential applications in architectural acoustics, room acoustics, and duct noise control. [ABSTRACT FROM AUTHOR]