ITS has a diversified service offer in terms of industrial acoustics / soundproofing engineering studies and design office activities, meeting the needs of original equipment manufacturers (OEMs) as well as those of end users with regard to the noise limitation of machines, equipment and facilities.
Engineering studies and design in industrial acoustics / soundproofing involving on-site measurements
ITS can carry out an industrial acoustics / soundproofing engineering study involving on-site measurements in various contexts :
- measurement of the noise exposure of employees of a company in specified locations e.g. at workstations, or overall in a workshop (or in any other space with machines or production, transformation or assembly lines) including in traffic aisles; it is then often a question of verifying compliance with the normative or regulatory requirements e.g. (in Europe in general, and therefore in France in particular) with respect to the European directive 2003/10/EC :
- for the daily noise exposure level L EX, 8h: 80 dB(A) and 85 dB(A) are the thresholds, respectively lower and upper, triggering the action; 87 dB(A) is the authorized limit value
- for the peak sound pressure ρpeak: 112 Pa i.e. 135 dB(C) and 140 Pa i.e. 137 dB(C) are the thresholds, respectively lower and upper, triggering the action; 200 Pa i.e. 140 dB(C) is the permitted limit value
- measurement of the decrease in sound level by doubling the distance from the source; (in France) it is then often a question of verifying (regulatory) compliance with the decree of August 30, 1990 taken for the application of article R. 235-11 of the labor code and relating the acoustic correction of the work premises - in the event of a daily sound exposure level greater than 85 dB(A), reverberation control measures for the premises, i.e. a reduction in the reverberation of sounds being then required :
- in the room empty of any machine or production facility: 2 dB(A) to 4 dB(A) is the authorized (lower) limit [1]
- after installation of production machines and devices: 3 dB(A) to 4 dB(A) is the authorized (lower) limit [2]
In the case of offices and other work premises, standard NF S 31-080 Acoustics - Offices and associated spaces - Acoustic performance levels and criteria by type of space, which is not of compulsory use, constitutes a reference document frequently used (in France), defining acoustic performance indicators (technical requirements) which can be, within the framework of an industrial acoustics / soundproofing engineering studies and design office mission, checked on site by an appropriate metrology :
- measurement of overall sound level: 30 dB(A) to 55 dB(A) is the recommended (upper) limit [3]
- measurement of the spatial decay rate: 2 dB(A) to 4 dB(A) is the recommended (low) limit [4]
- measurement of reverberation time: 0.4 s to 1.2 s is the recommended (upper) limit at mid-to-high frequencies i.e. for band central frequencies between 500 Hz and 2000 Hz [3]
With regard to problems of neighborhood discomfort, which often justify the intervention of an industrial acoustics engineering studies and design office, whether it is an establishment classified for environmental protection (ECEP) or not, ITS can carry out measurements :
- measurement of the sound pressure level; (in France), it is then a question of verifying compliance with a limit set by a prefectural decree, e.g. 60 dB(A) [5]
- measurement of emergence, i.e. the difference between the A-weighted equivalent continuous pressure levels of ambient noise (industrial site in operation) and residual noise (in the absence of noise generated by the industrial site, but measured over its functioning) :
- 5 or 6 dB(A) during the daytime [6]
- 3 or 4 dB(A) at night [6]
The measurements that can be carried out by an industrial acoustics / soundproofing engineering studies and design office such as ITS can be extended :
- determination (based on metrology) of the sound power level of noise sources e.g. according to standard NF EN ISO 3744 Acoustics - Determination of sound power levels emitted by noise sources based on sound pressure - Expertise method in conditions approaching those of the free field on a reflecting plane; it can then be a question of verifying the respect of the obligations of the manufacturers within the framework of the directive machines 2006/42/CE or within the framework of the directive 2000/14/CE on the noise of the materials used outside
- measurement of the difference in sound levels between the exterior and the interior of a construction :
- for industrial noise reduction devices e.g. according to standard NF EN ISO 11546-2 Acoustics - Determination of the sound insulation of enclosures - Part 2: on-site measurements (for acceptance and verification purposes) [7]
- for premises NF S31-057 Acoustics - Verification of the acoustic quality of buildings [7]
To carry out engineering and design studies in industrial acoustics involving on-site measurements, ITS has the required means :
- sound level meters and noise analyzers
- noise generators
Engineering studies and design works in industrial acoustics / soundproofing involving calculations & simulations
Many engineering studies and design works in industrial acoustics / soundproofing, as carried out by ITS, involve calculations & simulations :
- for the operation and analysis of acoustic measurement campaigns, carried out by ITS human resources or not; ITS has acoustic measurement data processing software and performs computer calculations
- when looking for and when developing solutions to improve a situation :
- calculations of the sound impact of noise sources (inside industrial premises or outside, with respect to the environment) with or without a noise reduction device (according to different scenarios in relation to an action plan); such evaluations must take into account the propagation mechanisms of sound waves (indoors or outdoors) and often involve sound attenuation (not only atmospheric), and other phenomena (absorption, reflection, transmission, diffraction)
- prediction of the acoustic performance (and, if required: in terms of thermal transfers, aeraulics) of noise attenuation devices
- partitions (for walls and dividers, floors, ceilings and roofs limiting the transmission of sound) for casings, cowlings, enclosures for machines and production lines, for soundproof buildings, for noise barriers and anti-noise walls
- silencers for fluids at ambient or moderate temperature (e.g. for air inlets and outlets of ventilation or air conditioning networks, refrigeration facilities, for air intake of compressors and boosters, heat engines, gas turbines, and for the innumerable materials including fans) or for gases at very high temperatures, such as for equipment for which takes place a combustion process (e.g. engines and generators, boilers, furnaces, turbines) or an expansion process of pressurized fluids (e.g. when using control valves, when venting to the atmosphere) and for industrial chimneys in all sectors of activity
ITS industrial acoustics / soundproofing engineering studies and design office is equipped with commercial software, e.g. with sound ray tracing to model the propagation in premises or based on FEM [8], BEM [9] calculations. The latter are used for the calculations of acoustics and aerodynamics in ducts (aeraulic networks and pressurized fluids) when the latter are not carried out with the SILDIS® software, developed by the human resources of ITS [10], which also presents functionalities related to the prediction of sound emissions from control and safety valves, sound propagation in enclosed spaces or outdoors, acoustic performance in terms of attenuation and absorption of multilayered structures.
Engineering studies and design in industrial acoustics / soundproofing involving sizing, recommendations
ITS' industrial acoustics / soundproofing engineering studies and design office missions often have to do with the sizing of soundproofing equipment such as absorbent wall linings, suspended absorbent elements, dissipative or reactive silencers, anti-noise walls, soundproof enclosures and cabins, when it is not a question of industrial buildings with high acoustic performance.
Selected from commercial products or developed to measure, the noise reduction devices studied by the ITS engineering office as part of industrial acoustics / soundproofing consultancy and design services have quantified acoustic performance, which can be subject to warranty and on-site verification as can be expected from an experienced consultant.
The recommendations of the ITS acoustician make it possible to solve the problems encountered in the fight against industrial noise, whether they are common (reduction at the source of noise emissions from machines, limitation of the propagation of noise in buildings or outside) or requiring high technicality (constructions for test benches and acoustic measurement rooms, silencers for large-capacity turbomachineries).
Globally
The quality management system set up by ITS for its industrial / soundproofing acoustic engineering studies and design office assignments is (as for its other design and software publishing activities) regularly assessed and certified as complying with the requirements of the standard. ISO9001; ITS services are covered by a professional insurance including a ten-year guarantee.
[1] depending on the floor area of the room compared to reference values 210 m2 and 4600 m2
[2] depending on the floor area of the room compared to reference values 210 m2 and 1000 m2
[3] depending on whether it is an individual or collective office, or an open space (open plan office), or a space to be fitted out, a meeting/training room, a relaxation area, a company restaurant or a circulation
[4] depending on whether it is an open space (open-plan office), a space to be fitted out or a company restaurant
[5] at the property line
[6] in regulated emergence zones (REZ), and depending on the context
[7] canceled standard, of persistent use
[8] Finite Element Method
[9] Boundary Element Method
[10] in a Research and Development (R&D) context