Acoustical absorption is measured by which of the following?

• A. The rate at which sound energy is transmitted through a partition.
• B. Sound intensity at a given point in space.
• C. Energy stored in a room is measured by decibel readings.
• D. Absorption coefficient and Sabins (area-based absorption).

Answer: (D)

Acoustical absorption is quantified by how much sound energy is absorbed by surfaces, not how much is transmitted or stored. The absorption coefficient (alpha) is the fraction of incident energy that a material removes from the sound field (0 to 1). Multiply this coefficient by the surface area that the sound encounters to get Sabins, the total area of absorbing material. This area-based measure (absorption coefficient and Sabins) directly reflects how effective the room is at damping sound, which is exactly what absorption describes. The other statements describe transmission through a partition, point-by-point sound intensity, or energy/storage levels in decibels, which do not capture the absorption process.