A review on innovative measures for improving the sound absorption of acoustic materials for broader frequency ranges

This review explores various types of acoustic materials that are modified to enhance their sound absorption properties. Effective noise control relies on materials with high sound absorption coefficients (SAC) across a wide frequency range. Porous materials, such as foams and fibrous structures, are commonly used for mid to high-frequency absorption, while resonator-based materials, including Helmholtz resonators and micro-perforated panels, target low-frequency sounds. Natural fibres offer a sustainable alternative, and composite materials combine different mechanisms for broader spectral absorption. To further improve performance, materials can be modified physically (e.g., structural alterations), chemically (e.g., treatments or coatings), or through advanced techniques such as nanotechnology and additive manufacturing. Mathematical models help analyse their acoustic behaviour, guiding material optimization. This review highlights the ongoing advancements in acoustic materials, emphasizing the need for innovative modifications to meet modern noise control challenges in architectural, industrial, and automotive applications.