Low-frequency broadband metamaterials for ventilated acoustic insulation

Abstract

Achieving effective sound insulation across a broadband range at low frequency while ensuring sufficient ventilation remains a significant challenge in the field of acoustic engineering, as there exist complex trade-offs in attenuation capacity, operating frequency, and opening size. Here, a double Archimedean spiral structure is proposed and then optimized using genetic algorithms. The sparse design, featuring ventilated channels on both sides of the unit, significantly expands the operational frequency range, effectively blocking over 80 % of incident energy within the 546–1575 Hz range. Its working mechanism can be attributed to the Fano-like resonance effect, which is further revealed by employing a mechanical analogy based on the spring-mass model. Moreover, the addition of foams and a reconfigurable modular assembly enhances both broadband sound reduction and flexibility. Consistency between numerical simulations and experimental results validate the potential for this approach in applications of ventilated acoustic insulation, offering advantageous theoretical and practical perspectives.