Recent progress in acoustic materials and noise control strategies – A review

• Recent advances of acoustic materials based on engineering materials and tailored structures. • In-depth discussions of sound absorption mechanisms of materials and structures. • Summary of noise control strategies of nano-engineered hierarchical structures. • Brief overview of modeling and simulation technique for acoustic wave propagation. • Challenges and opportunities for future research directions of acoustic materials. Noise pollution impacts the well-being of millions of people on a daily basis and can lead to serious health issues such as hearing loss and stress. Developing efficient yet cost-effective sound absorbing materials for noise reduction in vehicles, buildings and large spaces has become an important research area. The present review focuses on the latest developments in sound absorbing products based on engineering materials solutions as well as tailored micro and nanostructures. In addition, modelling techniques for simulating sound wave propagation through porous media are briefly introduced. Various materials such as polyurethane foam, thermoplastic foams, textile fabrics and composites are reviewed with different design strategies and structures ranging from foam structures to micro-perforated panels summarized and compared. The effect of different types of micro- and nanofillers, hierarchical and sandwich structures and synergistic effects of combining multiple constituents with structural designs at different length scales to achieve the desired acoustic properties are discussed. Mechanisms of each are analysed with the aim of exploring new strategies based on existing knowledge. Opportunities and obstacles are identified, while engineering applications ranging from automotive to built environment are reviewed, together with their desired properties and functions to shed light on future research directions towards advanced acoustic materials.