Acoustic properties of white polystyrene & higher density hard foam vs Rockwool

[Baldo]

Hi,

Can I ask what are the acoustic absorption properties of the Polystyrene panels? These are 600x1200mm panels of various thicknesses from 20mm to 50mm. They use them here as insulation under buildings and on walls.

There are also other hard foam like panels which are not really polystyrene but more of a hard type of foam. I think architects use it for making models and they also use these as insulation in buildings.

How are these materials when it comes to making sound absorbing panels instead of using rock wool or fibre glass? Will they do the job of absorbing the bass frequencies?

Let me know if you need me to provide any more information. If you like I can take pictures and upload them.

Many thanks.
Baldo

[Folderol]

Pretty poor.
Also polystyrene is the worst possible substance to have in your living space. If you are ever unfortunate enough to have a fire, you're dead! No ifs or buts.

[Wonks]

Expanded polystyrene is quite good at not transmitting sound, but that's because it reflects a lot back. So quite good for soundproofing and thermal insulation (if enclosed in suitable fire-resistant material), but not good for acoustic treatment in a studio.

As Folderol says, it's a real fire hazard if installed without a thermal barrier for protection.

Any other hard foam is likely to be closed-cell in nature and so, like polystyrene, is OK for sound insulation but poor at sound absorption within in a studio as most sound simply gets reflected back.

You need an open-celled foam, that lets sound waves penetrate right through and get absorbed as they do so.

[Sam Spoons]

Also polystyrene is very light, for sound insulation you need mass which it doesn't have much of.

[Hugh Robjohns]

Can I ask what are the acoustic absorption properties of the Polystyrene panels?

Next to zero, basically... although I expect they will damp the extreme HF to some extent.

Absorbers work by allowing air pressure waves to enter the material and lose energy by fighting its way through it. Hence the effectiveness of the tangled fibres of mineral wool, or the interconnected open-cells of foam.

If you hold the polystyrene panel up to your mouth, make a seal, and blow, I suspect you won't be able to... demonstrating that sound waves can't enter and no absorption can occur.

They use them here as insulation under buildings and on walls.

Yes, quite good as heat insulators... But not nice should they ever catch fire due to the toxic fumes produced. I wouldn't have polystyrene anywhere in my studio space!

There are also other hard foam like panels which are not really polystyrene but more of a hard type of foam. I think architects use it for making models and they also use these as insulation in buildings.

Don't know what that is... but try it with the test described above. If it is porous it might be useful in an acoustic sense... some acoustics foams are fairly rigid...

Will they do the job of absorbing the bass frequencies?

I'm opting for no... or at best, very unlikely!

H

[Mixedup]

polystyrene is the worst possible substance to have in your living space.

Yeah. You'd be better off covering the walls in diffusion made solely from kindling

[Wonks]

It's actually pretty hard to set light to. But once it does go, it goes.

[Studio Support Gnome]

Both are acoustically useless for absorption or soundproofing.

Both offer good mechanical linkage through rigid light structure , no useful absorption to speak off, either in soundproofing application, or in acoustic treatment.

FR polystyrene is commonly used for diffusors.

RPG's skyline type for example.

that's the limit of it's usefulness in the majority of cases.

(it can also be used in conjunction with concrete pour as a moulding material to produce diffusive structures, and slot absorbers , but that is the realm of the specialist environment )

[Baldo]

Thanks for this guys.

I shall have to get some Rockwool again and build the bass traps.

Saved me from spending too much time going down a wasted rabbit hole.