Environmental noise reduction by sonic crystals barrier

Noise barrier is widely applied as an effective approach to improve life quality of people by mitigating environmental noise that comes with booming transportation and urbanization. Compared with conventional noise barriers, sonic-crystal-based barriers stands out because of better noise mitigation performance at lower frequency while avoiding excessive airflow and visual obstruction. However, large thickness owing to multi-layer structure remains a challenge for practical application of sonic-crystal-based barriers. According to the generalized Snell’s law, a compact barrier composed by the novel shadowed-C-shaped (SCS) unit cells is designed with a much smaller lattice constant. Furthermore, the SCS unit cell is optimized to achieve broader band gaps in the frequency range below 5kH based on the Bloch’s theorem, thus improving the noise reduction performance. Simulation results show that the insertion loss of the optimal barrier is over 10 dB in broader band, especially around 800 and 1210 Hz. It is verified that the experimental insertion loss is basically consistent with the numerical results. The sonic-crystal-based barrier for traffic noise control in a compact thickness also shows a promising potential to be applied to various scenarios of noise control.