The input data useful for reducing the reverberation of a room are mainly:

- a physical indicator of the existing acoustic situation i.e. the exiting reverberation time (*)
- the use of the premise (*)
- the level of acoustic performance wich is required (desired reverberation time, desired sound pressure level, desired spatial sound decay) (*)
- the surfaces available for the implementation of absorbent materials (area of available surfaces, acceptability of overweight for wall supports or for roofs).

In very numerous cases, the reaction to fire of considered materials is also taken into account as well as considerations of appearance (architectural style, colors, materials ...).

In the case of realization in the food industry, in pharmaceuticals, or in hospitals, specific constraints related to hygiene are involved and may necessitate the use of particular absorbing coatings (with waterproof washable cover) or the use of stainless steels.

Other parameters may be involved such as the authorized mass, the required longevity or the available budget.

*limit values ​​of maximum reverberation duration (reverberation time) or of minimum equivalent absorption area must be taken into account for certain premises in tertiary buildings, minimum values ​​of spatial sound decay are to be considered for work spaces