A sound barrier is a physical or conceptual limit that prevents sound waves from traveling freely. This can occur in various environments, such as when sound waves encounter obstacles like walls or mountains. In aviation, the term also refers to the point at which an aircraft exceeds the speed of sound, leading to a sonic boom. In acoustics, sound barriers are often used in construction to reduce noise pollution. These barriers can be made from materials like concrete or wood and are commonly found along highways. Their purpose is to absorb or deflect sound waves, improving the quality of life for nearby residents.