The question of acoustic performance levels and criteria for work premises is central, when one considers the protection of workers against noise-related risks.
The Decree of August 1990 the 30th used for the application of Article R. 235-11 of the Labor Code and relating to the reverberation limitation of working premises is applicable to the construction or layout of working premises, where envisaged machinery and equipment may expose workers to a daily sound exposure level greater than 85 dB (A).
This document establishes the minimum characteristics that these rooms must have in order to reduce the reverberation of the noise on the walls when this must significantly increase the level of noise exposure of workers (the increase in exposure is appreciated in relation to what would be the exposure of each of the workers in the same premises ideally treated, that is to say without any reverberation).
The technical requirements of this decree are applicable where it is established that reverberation, as assessed by a predictive acoustic method, would result in an increase of the daily sound exposure level of a worker equal to or greater than 3 dB(A).
In what follows:
- S represents the floor area of the room (in square meters)
- DL is expressed in dB (A) per distance doubling
The walls of such spaces shall be so acoustically treated that the decay of the sound level by doubling the distance to the source measured in the empty space without any production machine or installation reaches at least the value given by a rule related to the workroom floor area.
- DL = 2 dB(A) if S ≤ 210 square meters
- DL = 1,5 log S - 1,5 if 210 < S ≤ 4600 square meters
- DL = 4 dB(A) si S > 4600 square meters
When the decrease in the noise level by doubling the distance at the source is measured in the room after installation of the production machinery and apparatus, the DL value which must be at least reached is given by another rule related to the workroom floor area.
- DL = 3 dB(A) si S ≤ 210 square meters
- DL = 1,5 log S - 0,5 si 210 < S ≤ 1000 square meters
- DL = 4 dB(A) si S > 1000 square meters
ITS masters all aspects of the question of acoustic performance levels and criteria for work premises:
- on-site measurements (by a technician qualified in physical measurements, specialized in instrumental techniques, with a duly calibrated and verified sound level meter) of the decrease in the sound pressure level by doubling the distance to a noise generator at distances standardized for the determination of the DL parameter mentioned above
- comparison with the regulatory values depending on the ground surface of the room and according to its lay-out status
- study of ways for improvement and advice for bringing work premises into compliance with the question of noise; simulation of the acoustic performance of different technical solutions (ceiling and other suspended sound-absorbing elements, wall cladding for soundproofing, noise barriers)
- marketing of noise reduction equipment and soundproofing work
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