Soundproofing Foam

Please let us clarify here our foam is sound absorbent but it is not Soundproofing if you buy acoustic foam thinking it will soundproof a room you will be disappointed. it may dampen noise to some extent but it will definitely not make a room soundproof.

Please read the section lower down the page titled  “How can you make a room more soundproof ?” and you will see a guide to improving a rooms soundproofing

This common misconception may arise from various reasons, firstly the term sound absorbent which is used widely in explaining how acoustic foam works. more on this can be seen on this page Sound Absorption.

Another factor maybe because you see it used so much in recording studios and may think it is there to stop sound traveling outside the room, the real reason has nothing to do with this it is to dampen the sound within the room in order to create a better recording environment. Soundproofing has nothing to do with it.

Acoustic Foam does not Sound Proof

noise

Acoustic foam may help somewhat with the high and to some extent mid frequencies. however it will do a lot less for the low frequencies, which have much longer wavelengths. For example if you stand outside a music venue or nightclub etc you hear the bass thumping through the walls if a thick wall cannot stop these low frequency sounds traveling through then a piece of foam has no chance.

To soundproof you need to isolate the sound which is a much more complex and costly undertaking than sticking some foam on a wall. In a recording environment this often done by making a room within a room (RWAR) as sound not only travels through air ( air borne sound ) it also travels through solid materials ( structure borne sound ) more info on sound isolation can be seen here.

How can you make a room more soundproof ?    Below is an article giving a little advice.

Acoustic tiles will reduce reverberation in the room, but won’t do anything for the sound insulation of the wall.

In order to improve the sound insulation of the wall you need to provide isolation and mass. The best way of doing this is to install a new wall leaf fully independent of the existing wall i.e.

1. Tack a layer of 12.5 mm British gypsum soundbloc plaster board on the existing plaster and lath wall (Provides mass and covers any holes, splits and gaps etc).

2. Provide a new stud (timber or metal) at least 25 mm from and completely independent of the existing wall. Fill the gaps between the vertical studs with British Gypsum Isover RD35 foil faced acoustic slab; the foil facing the existing party wall and the fibrous material facing into the basement – take care to make sure the slabs do not touch the existing wall by holding in place with straps or chicken wire. (the gap between the existing wall and new stud provides isolation, and the acoustic slab provides limited mass and reduces resonance in the new wall void)

3. Horizontally fix British Gypsum RB1 resilient bars to the room side of the vertical stud members at 450mm vertical centres (provides isolation).

4. Form a new wall surface on the room side of the stud by first fixing a layer of 19 mm British Gypsum Gyproc Plank to the horizontal resilient bars, avoiding fixing through to the stud framework underneath (its very important to fix to the resilient bars not the stud). Then over lay a layer of British Gypsum 15 mm FireLine plasterboard, again avoid fixing through to the stud framework underneath, with joints staggered so that they do not match those in the layer of Gyproc Plank underneath (Provides mass – important to use these PBs as this is they are the densest thickest PBs on the market, also important to use the different thicknesses as this compensates for the acoustic weakness each board will have at different frequencies of sound).

5. Skim and set the new wall surface, taking care to fill any gaps at the junction with the floor, ceiling or side walls with plaster and mastic.

6. Plant electric and heating services etc. on the new wall surface do not, repeat, do not; chase services through the new wall or otherwise penetrate it or you will be wasting money.

The above work can reduce sound transmission by 20 dB (four fold), but does mean losing around 125 mm of the room. You can reduce the room take by planting the above on battens fixed to the existing wall, but it is less effective. There is also a British gypsum fluff lined plaster board product called Tri-line that can be directly fixed to the wall, but is less than half as good as the independent wall leaf.

Further limits on the possible improvement in sound insulation come from:

a) the degree of sound insulation you already have from the wall i.e. it could be low so that the final amount after even complex works will not be very high.
b) flanking transmission via the ceiling and floor – but the direct route via the wall is normally dominant.

I avoid any building product marketed as being “acoustic” as they are rarely significantly more effective than normal products used intelligently, but usually cost a lot more.

The above advice is of course supplied without any implied or explicit liability on my part for the resulting effect or any collateral issues.