What is a Sabin in acoustics?

• A. A unit of area-based sound absorption (square feet or square meters of absorption).
• B. A unit of sound intensity.
• C. A unit of reverberation time.
• D. A unit of sound transmission.

Answer: (A)

Sabin is a unit of sound absorption area. It measures how much surface in a room effectively removes sound energy. The idea is simple: for a surface with area S and an absorption coefficient α (0 to 1), its contribution to the room’s total absorption is α × S sabins. The total absorption in a room is the sum of these contributions across all surfaces (and often across frequency bands). This area-based measure is what lets us relate absorption to reverberation time through the Sabine equation.

It’s not a unit of sound intensity, which would involve power per area, nor is it a unit of reverberation time (seconds), nor a unit of sound transmission. A sabin provides the abstract “absorbing area” concept: roughly, 1 sabin equals the absorption you’d get from 1 square meter of surfaces that perfectly absorb all incident sound. So, for example, a 100 m^2 wall with α = 0.5 adds 50 sabins to the room’s total absorption.