Topology-Optimized Omnidirectional Broadband Acoustic Ventilation Barrier

As a problem in acoustics, sound insulation finds wide applications in diverse situations. We design and experimentally implement an omnidirectional broadband acoustic ventilation barrier using a topology-optimization method. We propose a broadband acoustic barrier constructed of interlaced contraction structure with a central hollow channel, utilizing Bragg's scattering mechanism happening at impedance discontinuities. Based on this barrier, a density-based topology-optimization method is employed for the inverse design to broaden the sound-insulation band nearly 90% while keeping a low transmission. The topology-optimization method systematically optimizes the scatterers distributed at intervals in our initial barrier in dimensions of size, shape, and orientation to possess many complicated features, which produces the maximum reflection at a desired frequency range. Experiments with acoustic waves of different incident angles are conducted to validate the optimized design, whose results are consistent with the simulations. The measured ventilation rate of the optimized barrier reaches 60.8% compared to initial barrier (49.2%) due to the reduction of fill rate of solid material and aerodynamic loss, demonstrating a high ventilation effect. Our design opens routes to design sound insulators that enable applications to be air permeable yet sound proofing simultaneously.