Multiband omnidirectional ventilation acoustic barrier based on subwavelength gradient microcavity

Abstract Constructing artificial microstructural units that preserve free airflow while achieving efficient low-frequency sound insulation (<2000 Hz) remains a significant challenge for acoustic engineering applications. Here, we proposed an angularly gradient labyrinthine unit cell with gradually varying azimuthal spatial dimensions, enabling multiband sound insulation while maintaining ventilation. This design overcomes the limitation of traditional resonant units, which typically possess only a single low-order resonance. By tailoring the number of internal gradient units, multiband sound insulation effects can be achieved at subwavelength scales. The underlying physical mechanism primarily lies in the differences in the intrinsic resonance frequencies of the various gradient labyrinthine subunits. The results demonstrate that the proposed acoustic barrier maintains its multiband sound insulation performance ( i.e. , dB). Further, the structure possesses ventilation openings with an area duty ratio of up to 11.6%, thereby ensuring effective air circulation through the device. Numerical results further confirm the robustness of the sound insulation performance of the proposed acoustic barrier. This work demonstrates a feasible strategy for realizing a subwavelength ventilated acoustic barrier with multiband sound insulation, which is of great significance for the design of multifunctional acoustic devices and for applications in special scenarios such as simultaneous ventilation, heat dissipation, and noise reduction.