Which term describes the reduction of sound as it passes through a barrier between spaces?

• A. Transmission Loss
• B. Sound Absorption Coefficient
• C. Sound Transmission Class
• D. Mass-Loaded Vinyl

Answer: (A)

The idea being tested is how sound is reduced as it passes through a barrier. This reduction is described by Transmission Loss, a measure (in decibels) of how much sound power is prevented from getting from one side of the barrier to the other. It captures the barrier’s effectiveness and is typically evaluated across frequencies because a barrier doesn’t block all sounds equally at all frequencies—the higher the Transmission Loss, the less sound gets through. This concept is distinct from a single-number rating like Sound Transmission Class, which is a simplified summary of performance over a mid-frequency range and can hide how the barrier behaves at specific frequencies. It’s also different from the Sound Absorption Coefficient, which measures how much sound energy is absorbed by a material inside a room rather than transmitted through a barrier. And while Mass-Loaded Vinyl is a material used to increase a barrier’s mass and thereby improve Transmission Loss, it is not the measurement itself.