General information on acoustic insulation / soundproofing

Where to begin a process of struggle against noise

It is appropriate to begin a process of struggle against noise by taking the advice of professionals of soundproofing, such as Isolation Technologie Services, able to accompany a Client throughout his process of sound nuisance reduction by providing to him the expertise (of its human resource) of 20 years in the field of acoustics in all sectors of activity: industry, environment, energy, testing rooms, building.

What is soundproofing ?

Soundproofing involves the implementation of means of protection of workers against noise, and/or of environmental protection against noise, and/or of means for compliance with regulatory in terms of acoustics of buildings (industrial, tertiary, residential ...) Soundproofing can involve technologies related on the one hand to acoustic insulation and on the other hand to reverberation control as well as techniques related to the implementation of silencers and of noise barriers.

What is the difference between sound insulation and reverberation control?

The sound insulation is the set of processes implemented for getting a determined noise reduction, i.e. limiting the transmission of sound from one space where noise is generated toward another that one wishes to protect. The reverberation control consists in the implemention of absorbing materials in a premise in order to limit its reverberation time (the persistance of sound after a noise source has been shut off), and/or to increase its spatial sound decay, i.e. to improve the inner acoustics inside a premise by limiting the amplification of sound levels due to the phenomenon of reverberation.

Which means for reducing noise at source?

Noise reduction at source consists in reducing the sound power of a noisy hardware or equipment, by means such as an enclosure (acoustic hood) for a machine, a soundprrofing partition for a noisy area in a workshop for example, a silencer for a ventilation opening (or a suction / extraction linked to an industrial process).

Which means for limiting the spread of noise?

In a local limitation of noise propagation can namely be performed by the implementation of noise barriers (sound barriers) that oppose the propagation of noise in a given direction and also by the implementation of absorbent materials (according to the possibilities: in the form of a wall covering, and / or in the form of a suspended ceiling or suspended baffles and / or in the form of a floor covering) that allow to increase the spatial noise decay whereas limiting the amplification of noise levels due to the effects of reverberation. In some workplaces, cabins are constructions specifically designed to protect people (e.g. machine operators) of ambient noise, consisting of a fully enveloping structure.

Outside, the limitation of noise propagation can namely be performed by the implementation of noise barriers (sound barriers) that oppose the propagation of noise in a given direction.

In buildings, the performance of the envelope of a construction (housing, tertiary premise) in terms of airborne noise insulation limit noise propagation from noisy spaces toward spaces to be protected (interior or exterior). Booths for musician are constructions specially designed to enable them to practice music without disturbing the neighbors, consisting of a fully enveloping structure. Audiometric booths are constructions specially designed to allow examinations and tests related to the hearing, consisting of a fully enveloping structure.

Which protection of workers against noise in France and in the European Union?

In France, the decree of August 1990 the 30th is adopted in application of Article R. 235-11 of the Labour Code and is related to the reverberation control of working premises: this text is applicable in France in relation to the acoustic characteristics of working premises and in particular with respect to the noise level decay per doubling the distance to a noise source
In France, the Decree No. 88-405 of april the 21st amends the Labor Code and is on the protection of workers against noise. Note: all or part of this document has been modified by more recent texts
In France, the Decree No. 2006-892 of July 2006 the 19th is related to the safety and health regulations applicable for exposure of workers to risks arising from noise. This decree transposes Directive 2003/10/EC of 6 February 2003 concerning the minimum safety and health requirements regarding the exposure of workers to risks arising from noise.

In France, the Decree No. 2006-1044 of 23 August 2006 is related to the safety and health regulations applicable for exposure to risks from noise of staff employed on board ships
In the European Union, Directive No. 86/188/EEC of 12/05/86 is on the protection of workers against noise Note: all or part of this document has been modified by more recent texts
In the European Union, Directive 2003/10/EC of 6 February 2003 is concerning the minimum safety and health requirements regarding the exposure of workers to risks arising from physical agents (noise): applicable in French law since 2006 and involving in particular a decrease of 5 dB of limits previously in force

Which environmental protection against noise in France and in the European union?

In France: the Decree of August 20, 85 is on airborne noise emitted into the environment by classified installations for environmental protection with the exclusion of facilities subject to the provisions of the Decree of January 23, 1997 Rating: all or part of this document has been modified by more recent texts
In France, the Order of 10 May 1995 is on procedures for measuring noise from neighbors
In France, the Decree of January 23, 1997 relates to the limitation of noise emitted into the environment by installations classified for environmental protection
In France: the Order of 15 November 1999 amends Decree of 23 January 1997 on the limitation of noise emitted into the environment by installations classified for environmental protection and the Order of 14 May 1993 is on the glass industry
In France, the Decree of April 4, 2006 is relevant to the preparation of noise maps and of plans for prevention of environmental noise
In France, the Order of 5 December 2006 is on procedures for measurement of noise from neighbors
In France, the Decree of November 27, 2008 changes the order of 5 December 2006 concerning the measurement of neighborhood noise
In France, Decree No. 95-408 of 18 April 1995 is on the fight against neighborhood noise and amends the Code of Public Health
In France, Decree No. 2006-361 of 24 March 2006 is relevant to the preparation of noise maps and plans for prevention of environmental noise and modifies the code of Town Planning
In France, Decree No. 2006-1099 of 31 August 2006 is on the fight against neighborhood noise and amends the Code of Public Health
In the European Union, Directive 2002/49/EC of 25 June 2002 is on the assessment and management of environmental noise

Which noise regulation for residential buildings ?

In France, the Decree of 30 June 1999 relates to the acoustic characteristics of residential buildings: it is referred to as the "new acoustic regulation".

Which noise limitation in school ?

In France, the Decree of 25 April 2003 relates to the noise limitation in school.

end faq

Noise reduction by the means of an enclosure (soundproofing hood) or of a partition (acoustic)

Which are the input data useful for sizing the partitions of an enclosure (soundproofing hood)?

The input data useful for the design of the partitions of an enclosure - structure enveloping a sound source (machine), designed to protect the environment of this sound source (machine) - are mainly the conditions prevailing inside the envisaged enclosure (and the degree of aggressiveness with respect to the partitions that may result from the existence of projections such as cutting fluid in the case of a milling machine, water in the case of a water jet cutting machine for example), the existence of projections of solids (chips in the case of machining centers for example, silica in the case of a sander, etc ...), the thermodynamic state considered inside the enclosure (pressure, temperature, presence of vapors more or less inert), the level of acoustic performance required depending on frequency (insertion loss, remaining sound power) and also - where appropriate - the existence of additional constraints such as possibility of disassembly, reaction to fire, explosion resistance, need for partitions to provide thermal insulation, or to be translucent to allow the vision etc ...

In the case of realization in the food industry, in pharmaceuticals, or in hospitals, specific constraints related to hygiene are involved and may necessitate the use of particular absorbing linings (washable, waterproof) or the use of stainless steels. In the case of constructions located outside, the resistance to weather and to corrosion must also be taken into account, what may affect the definition of appropriate construction systems.

Other parameters may be involved such as the authorized mass, the required longevity or the available budget.

Whether small enclosures (cowls), or enclosures for single fixed machine (in the workshop, outside), or enclosures for large machine and for machine groups within which one can penetrate or mobile enclosures or even enclosures mounted on vehicles are concerned, the design of partitions must account the needs in terms of sound reduction (i.e. the ability to oppose the transmission of noise), the effects of amplification of sound levels related to the existence of the enclosure itself and also the accessibility needs in terms of gates whose effectiveness is related to the airtightness (rotating doors, sliding doors, folding doors, rolling doors) and also the needs of air circulation (ventilation, suction of waste ...), the needs for cuts for the passage of material flows (raw material inputs, outputs for finished products), the need for cuts for passages of ancillairies (cables, ducts, pipes ...).

These various inputs are necessary for the selection of products and of construction systems appropriate to the acoustic performance required for the partitions of an enclosure depending on the respective acoustic performance and area of its various subsets: acoustic insulation panels for facades, roof and floor where necessary, access, glass frames, silencers, cuts and openings.

Which metallic sound insulation panels for an enclosure (soundproofing hood) ?

With regard to metallic sound insulation panels (also called soundproofing panels) used for current applications in industrial soundproofing such as building an enclosure (acoustic hood) - structure enveloping a sound source (machine), designed to protect the environment of this sound source (machine) -, they generally consist of an outer casing (usually made of non-stainless steel, most of the time: with paint) and of an absorbing filling (quite often: mineral wool) covered by a surfacing (mostly: a fiber glass) and also a perforated protection (mostly: galvanized steel). For the outer casing, a powder coating usually provides the best possible protection against corrosion: classification up to C5 according to ISO 12944.

In some cases, the envelope of acoustic insulation panels of cabins can be made of stainless steel (SS 304, SS 316) or aluminum.

As required, the absorbing filling may consist of acoustic foam or polyester wool and, for some applications, be protected by a waterproof surfacing (polyurethane film and for extreme cases: painting).

In order to increase the sound reduction index in a given frequency range, an intermediate plate (usually made of steel) and an additional spacing absorbent layer may be inserted into the acoustic insulation panels, the performance of such insulation panels being based on the double shell effect.

For specific cases, a damping material (viscoelastic) can be incorporated.

Acoustic performance of sound insulation panels for cabins (in terms of sound reduction index) is very frequency dependent, being related mainly (besides the quality of the joint between panels basing their airtightness ):

- for panels with simple shell effect: mainly to the total mass density

- for panels with double shell effect: mainly to the mass density of each of the facings and to their spacing (the mass density of the inner absorbing lining may also be accounted if significant)

The prediction of acoustic performance of the partitions of an enclosure can be performed with the simulation software SILDIS.

The verification of acoustic performance of the partitions of an enclosure can be conducted in accordance with ISO 140-3 Acoustics - Measurement of sound insulation in buildings and of building elements - Part 3: Laboratory measurements of airborne sound insulation of building elements

Which performance in terms of sound insulation for an enclosure (soundproofing hood) ?

The performance in terms of sound insulation of an enclosure (acoustic hood) - structure enveloping a sound source (machine), designed to protect the environment of this sound source (machine) - is very frequency dependent and is primarily related on the one hand to the performance of acoustic insulation panels (characterized by their sound reduction index) and also where appropriate to that of the silencer (for ventilation) and also to the number and to dimensions of cuts and openings, and on the other hand to the sealing imperfections and to structure born (bridging) sound transmissions.

This performance can be expressed in terms of difference (with and without the enclosure) of overall A-weighted sound pressure levels or of sound pressure levels in octave bands at specified locations (such as maximum value at 1 m from the wall of the enclosure, average value on an enveloping surface, value at a workplace) - also known as acoustic pressure reduction -
of in terms of difference of overall A-weighted sound power levels or of sound power levels in octave bands of the enclosure - also known as acoustic power reduction or insertion loss od the enclosure-

For orders of magnitude (and with respect to a noise spectrum like "pink noise"), a level difference of up to 10 dBA can usually be obtained without special requirements, while a level difference from 10 to 20 dBA requires a standard enclosure without important leakage, while a level difference of 20 to 30 dBA requires a standard enclosure with sealing joints carefully implemented, a soundprrofing floor and a resilient mounting (enclosure with a vibration control system), and while a difference of 30 to 40 dB involves high performance enclosures carefully designed and installed (a level difference even higher shall involve a special construction).

The prediction of acoustic performance (for airborne sound) of an industrial enclosure can be performed with the simulation software SILDIS.

Verification of acoustic performance of an enclosure can be conducted (depending on the case) in accordance with the standard ISO 11546-1 Acoustics - Determination of sound insulation
performances of enclosures - Part 1: Measurements under laboratory conditions (for declaration purposes) or
in accordance with the standard ISO 1546-2 Acoustics - Determination of sound insulation performances of enclosures - Part 2: Measurements in situ (for acceptance and verification purposes)

Which ventilation for an enclosure (acoustic hood)?

The design and implementation of an industrial enclosure - structure enveloping sound source (machine), designed to protect the environment of the sound source (machine) - (carterization of machine tools, housing of noisy equipment or soundproofing building .. .) performing in terms of sound insulation necessitates the involvement of constructions often very airtight and often justifying moderate heat loss.

The ventilation of an enclosure is related to the need of evacuation of heat (calorific energy) dissipated by the enclosed equipment and not always transmitted through the wall of the enclosure.

The required ventilation rate is related to the thermal contributions of equipment installed inside the enclosure and to the performance in terms of thermal insulation of the partitions of the enclosure and also to the allowable temperature rise (difference between the temperature within the enclosure and the temperature of the air of the ventilation system).

With regard to thermal contributions in the workplace: those related to lighting, to computer equipment ... are generally minor, while those related to the process itself are often major and sometimes impacting the quality of the process itself: in the corrugated cardboard industry (where corrugators are concerned) or in printing industry (where rotary presses are concerned) for example. Where applicable, the presence of openings in the enclosure, permanent (passages for flow of raw material e.g. : wood entry for a planer) or temporary  (periodic opening of doors by an operator, exit through enslaved hatches of finished products for example outlet for blocks for of a concrete press) are taken into account as well as the air flow necessary for the process itself (in terms of air to be introduced into the enclosure for drying or cleaning with compressed air for example) or the flow rate evacuated through a network of dust or chip discharge (woodworking machine for example) or suction trimmings (processing machinery in corrugated cardboard industry, for example) if they exist.

As far as thermal contributions in the energy sector are concerned, (and in particular: in the case of power generation units), their treatment can be a major aspect for the success of a soundproofing project, enabling enclosed equipment to operate in conditions as foreseen by the manufacturers without exceeding the acceptable temperature limits: when one or more fan(s), engine(s), compressor(s), generator(s), gas turbine(s) are involved, for example. Are taken into account also the needs of combustion air (for an engine or a gas turbine for example) that may require the creation of an aeraulic circuit separate from the ventilation circuit of the enclosure with dedicated filtration and silencing equipment (silencer). For such projects, a comprehensive specific study in terms of aerodynamics is required.

The existence of a ventilation system in an enclosure generally leads to the need to implement silencers (one for the air inlet and one for the air outlet to limit the propagation of noise through these openings) and sometimes to have to silence the fan wich sound power can sometimes be of the same order as that of other noise sources for which the enclosure has been considered and may lead to the implementation of soundproofing equipment also consistent - if not more consistent - as for the treatment of the partitions of the enclosure . The installation of enclosures in some particularly hot environments (in relation to climate, or due to the presence of heat sources - nearby - such as a furnace or as some processes) may necessitate the implementation of equipment of air conditioning.

end faq

Improvement of the performance of an existing enclosure (acoustic hood) or wall (acoustic)

Why implement a lining of a metallic casing, of a metallic duct, a pipe, of a plasterboard partition, of a partition with wood sidings with a damping material to improve their acoustic performance?

A damping material can increase the sound reduction index of a plate on which it is applied.

Thanks to its damping properties, the damping material:

- reduces - other things being equal - the decrease of the sound reduction index (limits the sound transmission factor) of a thin plate for frequencies corresponding to the phenomenon of coincidence
- limits the impact noise associated with the fall of parts (containers, gutters ...) and/or limit the impact noise associated with material being ejected at high speed (duct for waste evacuation, for shavings in suction networks ...).

With its surface density, the damping material increases - all other things being equal - the sound reduction index (limits the sound transmission factor) of a thin plate at frequencies for wich the mass law is applicable.

Why implement a lining inside a metallic casing, a metallic screen, a partition or an enclosure made of plasterboard or with wood sidings with an absorbent material to improve their acoustic performance?

Absorbent material can increase the sound insulation of a plate on which it is applied (on noise source side).

With its absorption property, the absorbent limits the increase of sound pressure level on noise source side that would occur if the support alone (metal housing, plasterboard, wood plate) was interposed.

With its surface density (if it is not negligible), the absorbent material increases - all other things being equal - the sound reduction index (limits the sound transmission factor) of a thin plate at frequencies for wich the mass law is applicable.

Why implement a lining inside a metallic casing, a metallic screen, a partition or an enclosure made of plasterboard or with wood sidings with a material being damping and absorbent (acoustic complex) to improve their acoustic performance?

Un matériau amortissant et absorbant (complexe acoustique) permet d’augmenter l’indice d’affaiblissement acoustique et l’isolement acoustique d’une plaque sur laquelle il est appliqué en cumulant en un seul produit ne nécessitant qu’une seule application les propriétés complémentaires d’ amortissement de l’ amortissant et d’ absorption de l’ absorbant.

A material being damping and absorbent (acoustic complex) can increase the sound reduction index and the sound insulation of a plate on which it is applied by combining in a single product requiring only a single application complementary properties damping (of the damping) and of absorption (of the absorbent).

Why choose an absorbent or an acoustic complex based on polyester wool rather than any other absorbent?

Un tel choix est indiqué dans tous les cas ou il est recherché un produit justifiant d’un très bon facteur d’absorption et respectant l’environnement (car recyclable et sans défibrage) et dont l’application (dans les situations ordinaires) ne nécessite en général pas de surfacage.

Such a choice is appropriate in all cases where it is searched for a product showing a very good absorption factor and environmentally friendly (because recyclable and without grinding) and whose application (in ordinary situations) generally does not require any surfacing.

end faq

Protection of persons (from noise) by the means of a cabin (soundproofed or for soundproofing)

What are the input data useful for sizing the partitions of a cabin (soundproofed or for soundproofing) ?

The input data useful for sizing the partitions of a cabin - construction specially designed to protect people (e.g. machine operators) from ambient noise, consisting of a fully enveloping structure - are mainly the level of acoustic performance required by frequency (insertion loss, residual sound pressure level) and also - where appropriate - the existence of additional constraints such as the possibility of disassembly, the transportability, the reaction to fire, the need for the partitions to provide thermal insulation, or to be translucent to allow the vision etc ...

In case of constructions located outdoor, resistance to wether and to corrosion must also be taken into account, what may affect the definition of appropriate construction systems.

Other parameters may be involved such as the authorized mass, the required longevity or the available budget.

Whether control and monitoring cabins, or fixed booths for operators or even cabins mounted on vehicles are concerned, the sizing of the partitions must account the needs in terms of sound reduction (this is to the ability to oppose the transmission of noise), the effects of amplification of sound levels related to the existence of the cabin itself - specific constraints related to the acoustic comfort (speech intelligibility) and to the livability (visual aspect) inside may necessitate the use of particular absorbing linings, for wall, for ceiling or even for the floor - and also the needs in terms of accessibility whose effectiveness depends on the airtightness (rotating doors, sliding doors) and also the needs for air circulation (ventilation), the needs in terms of cuts for ancilliaries (cables, ducts, pipes ...).

These various input data are necessary for the selection of products and construction systems appropriate to the acoustic performance required for the partitions of a cabin depending on the acoustic performance and on the respective area of its various subsets: acoustic insulation panels for facades, roof and floor where necessary, access, glass frames, silencers, cuts and openings.

Which metallic sound insulation panels for a cabin (for soundproofing or soundproofed) ?

With regard to metallic sound insulation panels (also called soundproofing panels) used for current applications in industrial soundproofing such as building a cabin - construction specially designed to protect people (e.g. machine operators) from ambient noise, consisting of a fully enveloping structure -, they generally consist of an outer casing (usually made of non-stainless steel, most of the time: with paint) and of an absorbing filling (quite often: mineral wool) covered by a surfacing (mostly: a fiber glass) and also a perforated protection (mostly: galvanized steel). For the outer casing, a powder coating usually provides the best possible protection against corrosion: classification up to C5 according to ISO 12944.

In some cases, the envelope of acoustic insulation panels of cabins can be made of stainless steel (SS 304, SS 316) or aluminum.

As required, the absorbing filling may consist of acoustic foam or polyester wool and, for some applications, be protected by a waterproof surfacing (polyurethane film and for extreme cases: painting).

In order to increase the sound reduction index in a given frequency range, an intermediate plate (usually made of steel) and an additional spacing absorbent layer may be inserted into the acoustic insulation panels, the performance of such insulation panels being based on the double shell effect.

For specific cases, a damping material (viscoelastic) can be incorporated.

Acoustic performance of sound insulation panels for cabins (in terms of sound reduction index) is very frequency dependent, being related mainly (besides the quality of the joint between panels basing their airtightness ):

- for panels with simple shell effect: mainly to the total mass density

- for panels with double shell effect: mainly to the mass density of each of the facings and to their spacing (the mass density of the inner absorbing lining may also be accounted if significant)

The prediction of acoustic performance of the partitions of a cabin can be performed with the simulation software SILDIS.

The verification of acoustic performance of the partitions of a cabin can be conducted in accordance with ISO 140-3 Acoustics - Measurement of sound insulation in buildings and of building elements - Part 3: Laboratory measurements of airborne sound insulation of building elements

Which performance in terms of sound insulation for a cabin ?

The performance in terms of sound insulation of a cabin - construction specially designed to protect people (e.g. machine operators) from ambient noise, consisting of a fully enveloping structure - is very frequency dependent and is primarily related on the one hand to the performance of acoustic insulation panels (characterized by their sound reduction index) and also where appropriate to that of the silencer (for ventilation) and also to the number and to dimensions of cuts and openings, and on the other hand to the sealing imperfections and to structure born (bridging) sound transmissions.

This performance can be expressed in terms of difference (with and without the cabin) of overall A-weighted sound pressure levels or of sound pressure levels in octave bands at specified locations (such as maximum value at 1 m from the wall of the cabin, average value inside the cabin, value at a workplace) - also known as acoustic pressure reduction -.

For orders of magnitude (and with respect to a noise spectrum like "pink noise"), a level difference of up to 10 dBA can usually be obtained without special requirements, while a level difference from 10 to 20 dBA requires a standard cabin without important leakage, while a level difference of 20 to 30 dBA requires a standard cabin with sealing joints carefully implemented, a soundprrofing floor and a resilient mounting (cabin with a vibration control system), and while a difference of 30 to 40 dB involves high performance booths carefully designed and installed (a level difference even higher shall involve a special construction).

The prediction of acoustic performance (for airborne sound) of a cabin can be performed with the simulation software SILDIS.

Verification of acoustic performance of a cabin can be conducted in accordance with ISO 11957 Acoustics - Determination of sound insulation performance of cabins - Laboratory and in situ measurements

Which ventilation for a cabin (for soundprrofing or soundproofed) ?

The design and implementation of a cabin - construction specially designed to protect people (e.g. machine operators) from ambient noise, consisting of a fully enveloping structure - being efficient in terms of sound insulation makes it necessary to involve constructions often very airtight and often having moderate heat loss.

The ventilation of a cabin is related to the need for health air renewal ventilation for the occupants and may contribute to their thermal comfort (in summer: if the air introduced into the cabin is fresh enough, in winter: if the air introduced into the cabin is warm enough).

The required ventilation flow rate is related to the number of occupants, to the potential thermal disspation of equipment installed inside the cabin (lighting, computer equipment ...), to the performance in terms of thermal insulation of the partitions of the cabin and to the acceptable inlet temperature gradient (difference between the temperature within the cabin and the temperature of the air of the ventilation system). The existence of a ventilation system in a cabin usually leads to the need to implement silencers (one for air inlet and one for the air outlet to limit the propagation of noise through these openings) and sometimes to have to silence the fan (especially for the acoustic comfort of the occupants of the cabin). The installation of booths in some particularly hot environments (in relation to climate, or due to the presence - close - of sources of heat like an oven or due to the existence of certain processes in the paper industry, the cardboard industry or glass manufacturing for example) may necessitate the implementation of air conditioning equipment.

end faq

Limitation of noise propagation by the means of an acoustic screen (noise barrier)

Which are the input data useful for sizing the wall of an acoustic screen (noise barrier) ?

The input data useful for sizing the wall of an acoustic screen (noise barrier) are mainly the conditions prevailing in the environment of the envisaged acoustic screen (noise barrier) (and the degree of aggressiveness with respect to the wall that may result from the existence of projections of liquids such as water in the case of an outer shield along a road, for example), the existence of projections of solids (wood chips in the case of grinding boxes for example, gravel in the case of an outer shield along a road, for example, ballast in the case of a screen outside along a railway track for example), the level of acoustic performance required depending on the frequency (insertion loss, residual noise level) and also - where appropriate - the existence of additional constraints such as possibility of disassembly, reaction to fire, protection against radiation or heat, or the need for the wall to be translucent to allow the vision etc ...

In the case of constructions located outside, the resistance to weather and to corrosion must also be taken into account, what may affect the definition of appropriate construction systems.

Other parameters may be involved such as the authorized mass, the required longevity or the available budget.

Whether divisions of large rooms, or noise reduction for individual workstations, or protection of individual workstations from other workstations being more noisy, or road noise barriers, or railway noise barriers are concerned, the dimensioning of the wall must account the needs in terms of sound reduction (i.e. the ability to oppose the transmission of noise), the effects of amplification of sound levels related to the existence of the screen itself and also (especially for applications in the workplace) accessibility requirements in terms of gates whose effectiveness is related to the airtightness (rotating doors, sliding doors, folding doors, rolling gates), the need for cuts for the passage of material flows (raw material inputs, outputs of finished products), and also (when for example the treatment of thermal generation equipment or of cooling equipment is concerned) the needs for air circulation (ventilation. ..), the need for cuts for passages of ancilliaries (cables, ducts, pipes ...).

These different input data are necessary for the selection of products and of construction systems appropriate to the acoustic performance required for the wall of an acoustic sreen (noise barrier) dependent on the acoustic performance and on the respective area of its various sub sets: acoustic insulation panels, access, glass frames, silencers, cuts and openings.

Which acoustic insulation panels for an acoustic screen (noise barrier) in the workplace in the industry ?

With regard to metallic sound insulation panels (also called soundproofing panels) used for current applications in industrial soundproofing such as building acoustic screens (noise barriers) at workplaces in industry with respect to noisy machineries or equipments, they generally consist of an outer casing (usually made of non-stainless steel, most of the time: with paint) and of an absorbing filling (quite often: mineral wool) covered by a surfacing (mostly: a fiber glass) and also a perforated protection (mostly: galvanized steel). For the outer casing, a powder coating usually provides the best possible protection against corrosion: classification up to C5 according to ISO 12944.

In some cases, the envelope of acoustic insulation panels of cabins can be made of stainless steel (SS 304, SS 316) or aluminum.

As required, the absorbing filling may consist of acoustic foam or polyester wool and, for some applications, be protected by a waterproof surfacing (polyurethane film and for extreme cases: painting).

In order to increase the sound reduction index in a given frequency range, an intermediate plate (usually made of steel) and an additional spacing absorbent layer may be inserted into the acoustic insulation panels, the performance of such insulation panels being based on the double shell effect.

For specific cases, a damping material (viscoelastic) can be incorporated.

An acoustic screen (noise barrier) with two absorbent faces can be used in case of separation of two adjacent noisy workstations (boxes for hammering, grinding, deburring ...)

Acoustic performance of sound insulation panels for cabins (in terms of sound reduction index) is very frequency dependent, being related mainly (besides the quality of the joint between panels basing their airtightness ):

- for panels with simple shell effect: mainly to the total mass density

- for panels with double shell effect: mainly to the mass density of each of the facings and to their spacing (the mass density of the inner absorbing lining may also be accounted if significant)

The prediction of acoustic performance of the partitions of an enclosure can be performed with the simulation software SILDIS.

The verification of acoustic performance of the partitions of an enclosure can be conducted in accordance with ISO 140-3 Acoustics - Measurement of sound insulation in buildings and of building elements - Part 3: Laboratory measurements of airborne sound insulation of building elements

Wich efficiency for acoustic screens (noise barriers) ?

The effectiveness of acoustic screens (noise barriers) is very frequency dependent and is primarily related on the one hand to the performance of acoustic insulation panels (characterized by their sound reduction index) as well as when appropriate (for applications other than road noise barriers or railway noise barriers) - to the performance of silencers but also to the number and sizes of cutouts and openings, to sealing imperfections, and to the transmission of bridging noise. Moreover, this performance depends on the screen size and on the relative positioning of the noise source and receiver with respect to the acoustic screen (sound barrier) - and also on the size of the sound source -.

The prediction of the effectiveness of an acoustic screen (noise barrier) can be performed with the simulation software SILDIS.

Verifying the performance of a baffle (noise barrier) can be performed (as appropriate) in accordance with ISO 11821 Acoustics - Measurement of the in situ sound attenuation of a removable screen or NF EN 1793-1
Road traffic noise reducing devices. Test method for determining the acoustic performance. Part 1: intrinsic characteristics of sound absorption or NF EN 1793-2 reducing devices road traffic noise - Test method for determining the acoustic performance - Part 2: intrinsic characteristics related to the airborne sound insulation.

end faq

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