Absorption coefficient

Definition and scope


Determination of sound absorption coefficient or the equivalent absorption area of the building elements such as suspended ceilings, flooring textiles, mineral wool, wool plant, acoustic baffles, seats, ...

The measurement shall be performed in a reverberation room.

Evaluation method according to the NF EN ISO 354 standard

Expression of results: calculation of the single index αw according to NF EN ISO 1165

Consideration of αs values per octave between 250 and 4000 Hz with an accuracy of 0.05.

Vertical displacement of a reference curve by 0.05 jump until the sum of adverse deviations is the largest while remaining less than or equal to 0.1.

αw is the value given by while the reference curve at 500 Hz

There is no overall index for the equivalent absorption area within the meaning of standard NF EN ISO 11654, it is given in third octave. However, French law is based on an overall value which is calculated as follows: A = S x aw.

Example calculation test