Evaluation of noise barriers based on geometries and materials: a review.

The acoustical properties of a barrier are highly dependent on the physical properties of the material and the internal structure of the material. The acoustical material can curtail the quality of sound or enhance the dispersion, depending on the application being considered. The efficient acoustic performance of noise barriers possessing different shapes and materials including waste materials is reviewed for field implementation to achieve the low-cost sustainable noise barrier application in the Indian context. The review analysis of research papers demonstrates that the acoustic performance of barriers is dependent on different shapes, materials, and textures as well as onsite geometry. Based on the review study, T-shaped barriers with a soft top surface are found to be efficient at noise attenuation. For transparent barriers, perceived loudness and noise annoyance are assessed lower than that for opaque barriers and utilization of waste materials viz. plastic, rubber, bottom coal ash, etc. gives high noise attenuation along with low-cost efficiency. Noise pollution levels are high from prescribed noise limits in most of the Indian metropolitan cities. The Indian government is working on mitigation strategies of noise pollution as well as abiding laws regarding noise standards for the zone (residential, industrial, commercial, and silences) wise. In contrast, some communities which are adjacent to roads are suffering from high noise levels in the ambience. Therefore, it requires a coherent strategy for long-term measures intended at minimizing exposure of noise hence providing much more comfort to live, work, and shop near high-traffic roads. Noise barriers are highly beneficial in mitigating the emitted noise from the traffic.