Equivalent Absorption Area

Equivalent absorption area is the area of a perfectly absorptive surface (α = 1.0) that would absorb the same amount of sound energy as a given object, expressed in m² (metric sabins). For discrete objects like furniture, people, or suspended absorbers that cannot be described by a simple surface area and absorption coefficient, absorption data is published directly as equivalent absorption area per item. Per ISO 354 Annex B, discrete objects are tested by measuring the reverberation time change when the objects are placed in a reverberant chamber. Typical values include 0.4–0.6 m² per seated person, 0.1–0.3 m² per upholstered chair, and 2–4 m² per acoustic baffle unit. Equivalent absorption area is added directly to the total absorption in reverberation time calculations. It is the standard format for reporting the acoustic contribution of suspended absorbers, free-standing screens, and furniture in ISO 354 test reports.