The reduction of the reverberation of a room (due to the reflections of sound waves on the walls which delimit it and also on objects of different nature) is required in many contexts:
- spaces with young children
- classrooms and training facilities of educational establishments
- music rooms (with or without amplified music broadcast)
- sports halls and gymnasiums
- catering areas (e.g. canteens)
- work premises (e.g. workshops, open space offices, meeting rooms)
Depending on the case, the reduction of the reverberation of a room can be envisaged in the perspective of:
- improving speaking and listening comfort
- increasing confidentiality and discretion
- limiting of ambient noise levels e.g. with regard to the prevention of hearing risks
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 [1]
- the use of the premise [1]
- the level of acoustic performance wich is required (desired reverberation time, desired sound pressure level, desired spatial sound decay) [1]
- 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.
In the particular case of industrial premises, the location of noisy equipment (machines, production lines), their sound emission spectrum and the location of workstations (which one wishes to protect) constitute additional useful data in the framework of a project for which the objective is a reduction of the reverberated noise (resulting from the reflection of acoustic waves during their mean free path between the point of emission and the point of reception).
All of the useful input data for reducing the reverberation of a room can be used (as at ITS: by an acoustician qualified in building physics):
- for predictive acoustic calculations (in some cases: with numerical simulations based on sound ray tracing involving a 3D modeling of the considered space)
- for the selection or development of construction systemshaving appropriate acoustic characteristics (i.e. an acoustic absorption coefficient often as close as possible of 100 % in the frequency range of interest)
- for the prediction of values possible to be obtained, after works, for the reverberation time and when it makes sense, for the spatial sound decay, for the reduction of noise levels; of course the evaluation by ITS of these acoustic indicators before works is also possible
Soundproofing materials and corresponding installation works can also be marketed: ITS masters all aspects of the question of useful input data for reducing the reverberation of a room.
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[1] 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