The efficiency for the reverberation control of a room (in workplaces, in a building for tertiary use, in a building for residential use ...) is very frequency dependent and is mainly related on the one hand to the performance of absorbent materials which constitute the partitions or of which are covered the partitions of the room (characterized by their absorption coefficient or by their Sabine factor) and also to their area, and on the other hand to the geometry of the room, to its volume, to its fitting density and to the level of its acoustic quality before soundproofing. In some particular cases, humidity and room occupancy rates are also taken into account.

This performance can be expressed in terms of difference (with and without the implementation of materials for reverberation control) of reverberation times or (for rooms with a particular use) of averages of reverberation times at some frequencies.

For orders of magnitude, a difference of reverberation time (or of averages of reverberation times at some frequencies) up to 40% can generally be obtained without special requirements after implementation of a suspended acoustical ceiling (or of a net of suspended acoustic baffles) in the case of premises where the ceiling height is low enough and where the partitions were highly reflective before soundproofing (e.g. concrete walls, metal deck roof) whereas a difference of reverberation time (or of averages of reverberation times at some frequencies) above that shall involve a special achievement that may necessitate the implementation of absorbing wall panels.

This performance can also be expressed (namely in workplaces) in terms of difference (with and without the implementation of the materials for reverberation control) of the sound level decay per doubling of distance from the source.

For orders of magnitude (and with respect to a noise spectrum like "pink noise"), a difference of decay of the sound level per doubling of distance from the source up to 25% can usually be obtained without special requirements after implementation of a suspended acoustical ceiling (or of a net of suspended acoustic baffles) in the case of premises where the ceiling height is low enough and where the partitions were highly reflective before soundproofing (e.g. concrete walls, metal deck roof) whereas a difference of noise levels decay per doubling of distance to the source above must involve special achievement that may necessitate the implementation of absorbing wall panels.

This performance can also be expressed (namely at workplaces) in terms of difference (with and without the implementation of the materials for reverberation control) of overall A weighted sound pressure levels or of sound pressure levels in octave bands at specified locations well away from noise sources (in general: no value to a work station too close to a noisy machine).

For orders of magnitude (and with respect to a noise spectrum like "pink noise"), a level difference of up to 2 to 4 dBA can usually be obtained without special requirements at the end of implementation of a suspended acoustical ceiling (or of a net of suspended acoustic baffles) in the case of premises where the ceiling height is low enough and where the partitions were highly reflective before soundproofing (e.g. concrete walls, metal deck roof) whereas a higher level difference must involve a special achievement that may necessitate the implementation of absorbing wall panels.

Predicting the effectiveness of a the reverberation control of a room can be performed with the simulation software SILDIS®®.

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