As far as metallic wall panels for the reverberation control of a room are concerned (also known as acoustic insulation panels) such as those used for current applications in the field of industrial soundproofing or in premises of tertiary buildings, like reducting the reverberation of a room or increasing the spatial sound decay in a room, they generally consist of an absorbent filling (quite often: mineral wool) covered by a surfacing (mostly: a fiber glass) and also by a perforated protection (mostly: galvanized or painted steel).
Sound absorption of metallic wall panels for the reverberation control of a room
Sound absorption, which is obviously a fundamental characteristic of metal wall panels for the reverberation control of premises, depends on the characteristics of each of the layers present: filling, surfacing and perforated protection.
As required, the perforations of the protection of panels for reverberation control of a room can generally be circular (perforated plate) or in the form of slots (absorbent panels with metal blades).
Perforations (from left to right) circular (orthogonal or hexagonal arrangement), square or slotted perforations taken into account with the software SILDIS® for the sizing of room reverberation control panels
When the characteristic dimension of the holes and the perforation rate are large enough, the influence of the perforated protection is negligible i.e. the acoustic absorption coefficient of the rear layer (eventually: multiple) is almost unchanged, at the very least with regard to the frequency range whose 1/1 octave center frequencies are between 125 Hz and 4 kHz, as is commonly considered in the construction industry.
Otherwise, the coexistence of the holes of a perforated protection and a backing porous medium e.g. mineral (rock, glass) or polyester wool, foam (even: air) constitutes a resonator whose acoustic behavior is distinguished by the more or less selective character of the absorption of sounds wich is resulting (with regard to what the - multiple - choice of combinations of all kinds of dimensional parameters and of the airflow resistance of the rear porous medium makes it possible to modulate the performance with regard to the variation of the sound absorption coefficient depending on frequency).
In order to increase the absorption coefficient in a given frequency range, an intermediate plate (usually made of steel) and also a additional absorbent spacing layer may be inserted into the metallic wall panels, the performance of such absorbent panels then being (partially) based on the effect of resonant membrane (also known as resonator).
Such panels are then so efficient that they can then be used for acoustic measurement and testing rooms, e.g. anechoic rooms, aeroacoustic wind tunnels.
As for many other applications of multilayer structures involving mineral e.g. rock, glass or polyester wool, foams, plates e.g. steel, aluminum, metal, plaster - perforated or not -, the prediction of acoustic performance of metallic wall panels can be performed with the simulation software SILDIS®.
The verification of acoustic performance of metallic wall panels can be made in accordance with ISO 354 Acoustics - Measurement of sound absorption in a reverberation room.
Other technical characteristics of metallic wall panels for the reverberation control of a room
A powder coating usually provides the best possible protection against corrosion: up to classification C5 according to ISO 12944 whereas providing a visual aspect appropriate for the context.
In some cases, the frame of metallic wall panels (metallic absorbing panels) can be made of stainless steel (SS 304, SS 316) or of aluminum.
As required, the absorbing lining may consist of acoustic foam or of polyester wool and for some applications, protected by a waterproof surfacing (polyurethane film and for extreme cases: painting).
When required, metal wall panels for reverberation control can be matched with dividers, when these hardware are combined as part of the same soundproofing project (e.g. in shared offices, in the form of open spaces).
Whatever the reasons, metal panels are not always the preferred solution for the reverberation control of a room, in which case different alternatives can be proposed, with equivalent performance in terms of sound absorption, but sometimes with an aspect better harmonized with some visual atmospheres taking into account architectural preferences or particular furniture (e.g. for premises welcoming young children, for some dining rooms, meeting rooms, training rooms):
- panels with perforated protection in plaster (gypsum) or wood
- panels without perforated protection i.e. with a fabric surfacing
ITS masters all aspects of the question of the choice of metal wall panels for the reverberation control of a room.
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