Sound barriers, primarily used for noise reduction on highways, expressways, elevated composite roads, and other noise sources. They are divided into reflective sound barriers, which are purely for noise reflection, and composite sound barriers that combine absorption and reflection, the latter being more effective. Refers to wall-like structures installed alongside railways and highways to mitigate the impact of traffic noise on nearby residents. Soundproof walls are also known as sound barriers. A facility inserted between the sound source and the receiver to significantly reduce the propagation of sound waves, thereby diminishing the noise impact in a certain area where the receiver is located, is called a sound barrier. These are categorized into traffic noise barriers, equipment noise attenuation sound barriers, industrial boundary sound barriers, and are widely used on highways and expressways.