Which wall type is the least effective in preventing sound transmission to the other side of the room?

The 9" Concrete Hollow Block (CHB) Wall is the least effective in preventing sound transmission due to its construction and material properties. CHB walls tend to have a lower mass compared to solid materials like brick or concrete, which can diminish their ability to block sound effectively.

Sound insulation relies heavily on the mass of the wall, as denser and heavier materials are typically more capable of absorbing and blocking sound waves. The air gaps within CHB can act as conduits for sound to travel through, further reducing its effectiveness.

In contrast, the other wall types, such as the 12" Double Brick Wall, possess higher mass and are constructed in a way that generally offers better soundproofing capabilities. Therefore, while various factors such as wall density, structure, and material composition influence sound transmission, the characteristics of the CHB wall make it less suited for sound isolation.