ITS will participate in a noise reduction project in a dining room to improve acoustic comfort around Lyon (in the Auvergne Rhône Alpes region, in France).

The works following a complete acoustic diagnosis carried out by ITS (sonometric metrology on site, dimensional measurements, design office work with performance simulation with a computer, and recommendations for soundproofing solutions) will be carried out by a specialized installation team in a nursery: in a space dedicated for being the canteen.

Indeed, the reduction of noise in a dining room for the improvement of acoustic comfort is not only reserved for restaurants and other establishments of a certain standard, when it is desired for such a place to be either (depending on the context) friendly enough for guests or with an acceptable level of habitability for users.

This imposes special precautions in terms of:

  • no overcrowding (for what limit values for the number of places per floor area square meter, which vary according to ambition, may make sense)
  • layout (in relation to what the greater or lesser distance between tables is a parameter of interest)
  • constructive and layout provisions (presence of materials with sufficient quality e.g. with regard to sound absorption and sufficient quantity, presence of obstacles preventing sound propagation e.g. screens with acoustic properties).

Otherwise, the situation may come close (of course: more or less, depending on the case) to that described by the writer George Orwell in his bestseller "1984".

Regarding the general atmosphere of a place which is said to be a canteen: "... deafeningly noisy. "(p.66) [1] with the consequence (it is said that it is when someone asks something of someone else) that one speaks "... raising his voice to overcome the noise. "(p. 69) [1]

Regarding the feelings of a user "Lunch in the hot, crowded, noise-filled canteen was torment. ”(p. 138) [1] ; and, about two users of whom it is said that one (Parsons) "drops into the next seat" of the other (Winston) "The irritating thing was that in the racket of voices Winston could hardly hear what Parsons was saying, and was constantly having to ask … to be repeated. ”(p. 138) [1]

If "1984" is generally regarded as a dystopian novel (therefore, by definition, appealing to the imagination of the author), the drawbacks and inconveniences described in these passages of the book are, indeed, those actually ordinarily observed in a restaurant or in any other dining room (e.g. canteen, refectory, soldier’s evryday fare place, officers's mess or quarters, private lounge, banquet hall, snack bar, brasserie, pub) in which acoustic comfort has been neglected.

As mentioned above, limiting the number of guests or users (as the case may be) and the spacing of tables can usefully be supplemented, when the objective is the noise reduction in a dining room, by actions of which the study and implementation are a major activity for ITS, whose human resources have in this area an experience acquired over several decades.

Controlling the reverberation of the considered room is a major issue with a view to providing a sufficiently quiet dining room, where ambient sound levels remain within acceptable limits, speech intelligibility being (without having to raise one’s voice) sufficient, just like the privacy of conversations.

To do this, a selection of materials having suitable sound absorption properties, depending on the frequencies to be considered (most of the time: in an interval covering the bands of central frequency 500 Hz, 1 kHz, 2 kHz corresponding to the human voice) is necessary: they must of course take into account requirements linked to other technical criteria (e.g. reaction to fire, weight with respect to what is admissible for the supports e.g. walls and ceilings or under-roofs), decoration, and such soundproofing materials must also be affordable.

Installed as wall coverings, in the form of ceilings or suspended elements, in the form of screens placed on the floor (on legs or on wheels): different installation methods of those sound absorbing materials can be combined within the context of the same project to contribute to the overall acoustic performance of an enclosed space ; these materials limit (all the more so as their sound absorption coefficient is close to 100% and all the more so when they are installed in large quantities) the reflection of sound waves on hard walls, which is the basis of the reverberation phenomenon i.e. the persistence of a sound after extinction of a noise source.

The reverberation time (usually expressed in seconds, and corresponding to a sound decay with a ratio of one millionth) and the spatial decay of the sound level (in dB per doubling of the distance from the source : 6 dB in free acoustic field) are major sound quality indicators of a room (moreover not only a dining room but also a sports room, an office room or another work space), which can be:

  • measured by ITS: before work (to assess the extent of the improvement to be considered in the context of compliance upgrade), or after soundproofing (to assess its effectiveness)
  • calculated in advance by ITS (using commercial or in-house developed software) taking into account different soundproofing scenarios
  • guaranteed by ITS when soundproofing work is entrusted to one of its commercial partners (which ITS then advises on the implementation methods conditioning the expected acoustic result)

This realization will be added to the many others already accumulated by the human resources of ITS in terms of noise reduction in a dining room for the improvement of acoustic comfort: the user feedback relating to this project will be used on the occasion of a future realization, to the good completion of which it will be brought, as always, all the necessary care.

[1] pages numbering based on the French version in the Folio collection, Gallimard 2018 (the first edition of the novel dates from 1949)

Acoustic comfort in buildings

end faq