NCIDQ IDFX Practice Exam

What is primarily responsible for the control of sound transmission in buildings?

1. Barrier's weight

2. Barrier's elasticity

3. Barrier's mass

4. Barrier's height

The correct answer is: Barrier's mass

The primary factor responsible for controlling sound transmission in buildings is the mass of the barrier. Mass plays a crucial role in sound insulation because denser materials impede the movement of sound waves more effectively. When sound waves encounter a heavier barrier, the energy of the sound waves is absorbed and dissipated rather than transmitted through the material. This is known as the mass law, which suggests that as the mass of a barrier increases, the sound transmission loss improves. While there are other characteristics, such as elasticity and height, that can influence sound transmission properties, they are not as critical as mass. Elastic materials can help reduce impact noise, but they do not stop airborne sound as effectively as dense, massive barriers. Height does not significantly contribute to sound blocking effectiveness when compared to how much sound a material can absorb based on its weight. Therefore, focusing on the mass of construction materials is key to achieving better sound control within a building.