The acoustic absorber (or sound-absorbing material) is a type of materials used in the acoustic conditioning of rooms, due to their ability to absorb most of the sound wave they receive. Therefore, by reflecting a very small percentage of the incident sound, unwanted "Reflection (sound)") bounces are avoided, which can harm the acoustics of the room by introducing distortions.

In the professional field, the absorption capacity of these materials will have been calculated in laboratories and in the technical specifications of each material, its absorption coefficient and the critical frequency for each determined thickness will be given.