Metamaterial acoustic barriers for traffic noise control in urban zones

In recent years, research has explored the use of metamaterials in fields such as acoustics, mechanics, and medicine. Acoustic metamaterials are engineered to control sound wave propagation through geometric structures that induce resonance and periodic arrangements. These materials can be classified into various geometrical types—such as fractal, coiled, zigzag, helicoidal, and spiral—each offering specific acoustic behaviors. This classification aids in understanding their design and potential applications. This study presents a methodology for developing a new metamaterial using small-scale prototypes (MSSP) to mitigate traffic noise in urban areas. A 1:10 scale 3-D model, built with PVC square bars—with and without porous polyethylene layers—was used to simulate an acoustic barrier. A Brüel & Kjær Class 1 Sound Level Meter (BK 2270) measured the sound signals passing through different metamaterial configurations. These configurations involved alternating rows of bars with regular spacing to form periodic geometries. The resulting insertion loss was analyzed in the frequency domain. Results showed that the prototypes effectively controlled sound propagation, and the polyethylene layer enhanced noise absorption across a wide frequency range. This confirms the potential of geometrically designed metamaterials in developing efficient noise barriers for urban environments.