Advances and integration of noise reduction materials and structures: A review of porous materials and acoustic metamaterials

As modern society advances, activities such as industrial production, transportation, and urban construction inevitably generate considerable noise, profoundly affecting both the living and working environments. Consequently, the development of noise reduction technologies has become crucial. Among them, porous materials and acoustic metamaterials have garnered widespread attention as conventional and emerging solutions. Their distinct acoustic properties and mechanisms offer various approaches to noise attenuation. Porous materials effectively absorb high-frequency noise and exhibit broad absorption bands. Meanwhile, ingeniously designed acoustic metamaterials offer promising strategies for addressing low-frequency noise, spurring innovations in noise control. In recent years, there has been a notable trend toward the integration of porous materials with acoustic metamaterials, as well as the fusion of different types of acoustic metamaterials. Additionally, acoustic metamaterials are increasingly being combined with mechanical, novel materials and circuit technologies. This convergence not only enhances the overall performance of noise reduction solutions but also opens new avenues for developing advanced, multifunctional noise control systems. Against this background, this paper reviews the recent research progress of foam materials, fiber materials, and composite porous materials within porous materials, as well as Helmholtz resonators, microperforated panel absorbers, and membrane-type acoustic metamaterials within acoustic metamaterials. Furthermore, it also examines the research advancements in mechanical control and electric control technologies for tunable acoustic metamaterials. Additionally, this paper identifies current research gaps, predicts future development trends, and aims to provide guidance and insights into the advancement of the application of porous materials and acoustic metamaterials in noise reduction.