Acoustic metamaterials for low-frequency noise reduction: a review

Acoustic metamaterials offer innovative solutions for broadband and low-frequency sound absorption. Conventional porous materials, while effective in sound absorption, face limitations in dealing with low-frequency noise and complex structural applications. The studies on folded metaporous materials, double porosity metamaterials, hybrid acoustic metamaterials, and acoustic black holes have shown significant advancements in achieving efficient sound absorption across various frequency ranges. With their ability to overcome traditional material constraints and enhance sound absorption in both low and broadband frequencies, acoustic metamaterials hold great promise in creating quieter and more livable urban environments.