The prevention of noise in a school restaurant room (canteen) is a major imperative for a space whose purpose is not only, during a meal, to allow schoolchildren to nourish, but also to offer them an ambiance conducive to the necessary relaxation between learning sessions (which sometimes put them through the mill) and to desirable communications between classmates (which can then take place without being considered, as they would be in the classroom, as unwanted gossip).
This is why precautions must be taken with regard to the acoustic quality of school restaurant rooms (canteens) with a view to preventing noise:
- it is a question of limiting the reverberation of sounds, i.e. the reflection of sound waves on hard walls
The floor is usually not a very used way of improving, even when - as often ? - originally tiled (then: with an ultra-poor sound absorption coefficient since of the order of 0.01 i.e. 1% [1] at medium-high frequencies [2]), because the implementation of absorbent linings often faces cleanliness requirements, whereas their sound absorption index [3] at best reaches values of the order of 0.10 i.e. 10% [1] when it comes to the carpets available (on the market) being the best as to their acoustic performance.
The ceiling, the under-roof, on the other hand, are of particular interest with a view to preventing noise in a school restaurant room (canteen). Indeed, they often constitute a significant deposit of areas available for the installation of materials whose sound absorption index [3] can reach values of the order of 0.90 i.e. 90% or even 1 i.e. 100% [1] therefore quasi-maximum or maximum.
- they often take the form of suspended ceiling tiles (horizontally or under sloping roof i.e. following the slope of the roof, if applicable), placed on a metal frame, and which can integrate lighting devices
- they sometimes take the form of other suspended elements (horizontally, under sloping roof i.e. following the slope of the roof, if necessary or even vertically). In this regard, it should be noted that suspended elements with high sound absorption, i.e. whose coefficient of sound absorption coefficient or index are maximum [1] [2] [3] can usefully be installed in addition to an acoustic ceiling or an under-roof, a fortiori if these (e.g. when there are good reasons for keeping them as they are) have a poor acoustic performance (intrinsic, linked to their sound absorption coefficient), or if they are at heights so great that their in-situ efficiency is reduced
As for the walls, they are often able to receive more or less significant quantities of materials whose acoustic absorption index [3] can (there too) reach values of the order of 0.90 i.e. 90% or even 1 i.e. 100% [1] therefore quasi-maximum or maximum, once the areas unavailable due to the presence of doors, windows and other glazed surfaces, openings to adjoining rooms, equipment (e.g. furniture, coat-racks) are deduced. The need for mechanical protection in the lower part can lead, for such locations, to the use of panels with a reinforced surface layer (in wood or metal) (then: perforated with holes, or else with slots separating blades) which influences the acoustic performance of such soundproofing devices (sometimes called Helmoltz resonators).
- it is a question of opposing the propagation of noise, i.e. of putting in place (between tables or between groups of tables) obstacles through which sounds are not transmitted, which avoids the bouhaha which otherwise results from the accumulation of noise emissions in the restauration room
Claustras constitute the form concretely implemented for devices for which such functionality is expected: it is - obviously - preferable that they include materials whose sound absorption index [3] can reach values of the order from 0.90 i.e. 90% or even 1 i.e. 100% [1] therefore quasi-maximum or maximum.
- they often take the form of elements on legs or on wheels
It should be noted that their installation requires - obviously - not too cramped premises, so that passages compatible with the desirable traffic conditions are kept, for children as well as for service personnel.
These are the means of preventing noise in a school restaurant room (canteen), the feasibility of implementation of which must be studied on a case-by-case basis, depending on the constraints of each project, whether it is a new construction or a retrofit for which sound insulation in buildings should be envisaged.
This can never be said too much: it is a necessity for who wants to comply (can it be otherwise ?) with the applicable regulations (in France), formalized by a Decree of April 25, 2003 relating to the limitation noise in educational establishments.
ITS participated in a project of noise prevention in a school restaurant room (canteen), in the Nantua region, in the Ain department in the Auvergne Rhône Alpes region (France).
The reverberation time measurements carried out before the works revealed a non-compliance in terms of reverberation time, with respect to the applicable regulatory texts.
The study carried out made it possible to select, from among those reviewed, the best solutions for combinations of materials (fixing for each: nature, location, quantity) absorbing sound appropriately: a partial covering of the walls and the sub-face of the ceiling (by means of horizontal absorbing elements, suspended in front of the existing one, preserved because having been renovated very recently, before the intervention of ITS) was selected.
The lack of precaution when choosing (prior to the involvement of ITS in the project) a ceiling system (in a context of renovation) had resulted in a lack of comfort in this room, in which the phenomenon of reverberation was not mastered: everyone speaking louder to try to be heard contributed to the brouhaha, which had been the cause of complaints that motivated the recourse to ITS.
Such disorders will never happen again : the work carried out (installation during the school holiday period) enabled compliance, using (with regard to the problem posed) a tailor-made and turnkey solution in terms of noise prevention in a school restaurant room (canteen).
[1] on a scale of 0 to 1 i.e. 0 to 100%
[2] where noise emissions are highest, when human voice is involved
[3] calculated by taking into account the entire reference sound spectrum in the building sector i.e. the frequency interval of octave bands with central frequencies from 125 Hz to 4 kHz, with a weighting