A review of ventilated acoustic metamaterial barriers

<p indent="0mm">As urbanization accelerates, noise pollution has become a global environmental issue, significantly disrupting normal activities and human health. Ventilation soundproofing technology can effectively block noise while maintaining air circulation. This technology not only aligns with the concept of green soundproofing, improving people’s quality of life and health, but also contributes to energy conservation, environmental protection, and sustainable development. Acoustic metamaterials, a class of artificially engineered materials with special physical properties achieved through carefully designed internal structures, have garnered significant attention in recent years. These materials, with their unique properties and subwavelength dimensions, greatly enhance the ability to manipulate sound waves, leading to novel phenomena and broad applications, including abnormal transmission and reflection, super absorption, and topological effects. Notably, there have been groundbreaking advancements in ventilated acoustic barriers. This paper reviews the latest research progress and applications in this field, focusing on three main physical principles: Local resonance, interference cancellation, and phase gradient. The local resonance type includes reflective and absorptive variants. Local resonance ventilated acoustic barriers use the resonance effects of local structures to scatter and absorb sound waves. Interference cancellation ventilated acoustic barriers precisely control the geometric structure and arrangement within the material, causing incident sound waves to generate phase differences, creating destructive interference effects that weaken or cancel out the energy of the sound waves. Phase gradient ventilated acoustic barriers introduce phase gradient metasurfaces within the material or structure to alter the propagation path of sound waves, thereby achieving sound wave control. These principles control the propagation, reflection, or absorption of sound waves through different mechanisms, achieving both soundproofing and ventilation functions. Due to their subwavelength dimensions, metamaterial-based ventilated acoustic barriers are compact and suitable for wide-angle incident noise. Initial metamaterial designs focused primarily on single-frequency sound wave manipulation, but as research progresses and the demand for broad-spectrum environmental noise control increases, more designs are shifting towards broadband development. The paper also introduces new design ideas and optimization methods for complex application scenarios, such as the application of flexible materials, active metamaterials, and design optimization through artificial intelligence and machine learning. These innovative approaches not only rely on traditional material selection and structural design but also incorporate advanced technologies and interdisciplinary thinking, driving the development of ventilated acoustic barrier technology forward. Finally, the paper provides a summary and outlook. Acoustic metamaterials have shown great potential in the field of ventilated soundproofing, achieving performances that traditional materials struggle to match due to the unique structural designs inherent in acoustic metamaterials. The research and application of acoustic metamaterials are rapidly developing. By combining various innovative methods and technologies, more efficient, intelligent, and multifunctional soundproofing and ventilation solutions will be realized in the future. Although the trade-off between soundproofing performance and ventilation efficiency has not been completely resolved, continuous technological advancements and interdisciplinary integration will enable acoustic metamaterials to demonstrate their enormous potential in more fields, creating a more comfortable and quieter living environment.