Soundproofing a hall for amplified music (such as a discotheque or dancing club, a concert hall, an auditorium) is not only necessary (for the envelope of the building which must oppose sufficiently the transmissions noise), which is based on the respect of an emergence limit value i.e. the difference between the A-weighted equivalent continuous pressure levels of the ambient noise (hall for amplified music in operation) and residual noise (in the absence of the noise generated by the hall for amplified music but measured over its period of activity). In France, in the matter: a recognized offense exposes the offender to sanctions, as provided for in the Code of the environment.
Indeed, soundproofing a hall for amplified music is just as essential in a perspective of hearing protection for the public that frequents the hall: it is not to exceed the values - of 105 dB(A) as average level and 120 dB(C) as peak level - imposed by French regulations. But without proper consideration of the internal acoustics of the room in which is amplified music played, the sound levels are increased because of the phenomenon of reverberation (bearing in mind that, all other things being equal, the noise transmitted towards the outside is all the more important.
Finally, and it is not nothing, soundproofing a hall for amplified music is essential for the quality of listening, relating to internal acoustics of the place: the intelligibility of the speech and of the music are also dependent on the more or less careful consideration of the room reverberation.
If nothing is done, the reverberation time of a space, such as those ordinarily considered for playing amplified music, with an ordinary level of ambition, can reach (e.g. at high frequencies) nearly 2 seconds in a room with a volume of barely more than 1100 m3, which is considerable, illustrating a poor acoustic performance.
What happens then ?
- In the hall, those who had the bad idea to spend a moment (expected to be nice) in such a hall do not stay (very) long (which is not good for the bar activity or for the catering services which are often associated), and these one-evening (or one-afternoon e.g. for a dancing tea) spectators will not come back (in any case: not as often as desirable). Over time (word of mouth does not help, on the contrary), the attendance will decrease, which will not fit the purpose of the operator of the hall for amplified music.
- On stage (if it comes to live music or show), the unfortunate musicians (who then curse the manager who found them an engagement with such bad conditions, sometimes: for working, always: for practicing their art) have the greatest difficulty in making adjustments (voice, instruments, sound system, electro-acoustic hardware) which, in other rooms where the acoustics have been taken into account as they should, allow them to exercise all their talents and to be valued by the audience. And this is on this that their popularity, and therefore their success and their longevity in this activity depends: will they come back (as often as desirable for the operator with respect to its programming constraints) to perform in an environment being so hostile for the hearing and therefore being so poorly favorable for the enhancement of the quality of their scenic appearance ?
It is in this context that ITS took part in the soundproofing of a hall for amplified music near Lyon (France, Rhône-Alpes-Auvergne region).
It came to a dance club, whose acoustics were improved by the installation, according to the recommendations of ITS following a study of the reverberation of the considered space (measurements on site, calculations, simulation of acoustic performance): on the one hand of a suspended ceiling and on the other hand of an absorbing wall lining. The material chosen for the realization of the works had excellent characteristics in terms of sound absorption (almost 100% at medium and high frequencies). It was of course incombustible, to meet the requirements of the regulations for the prevention of fire risks ; it was black in color to match other decorative elements.
Satisfaction, evaluated at the end of the works with the operator (this latter considering the feelings and the feed-back of his customers, accustomed or passing, for the auditory comfort of this musical place ?), was expressed as being total for what related to the sound quality of this hall for amplified music, which will never be the room with poor acoustics it has been too long.
There is nothing to stop this place (which is also very welcoming both in terms of staff and infrastructure) becoming a must (at least: regional) in terms of nightclub or concert hall.
Mission accomplished for ITS !