Thread: Sound Reduction Panels

Hi Chris,
you may want to check the link below with similar product from Selby store in Melbourne which may save you a bit on postage

10pk 30x30cm Wedge Sound Foam Panels Tiles Acoustic Treatment SA3300 | Selby

cheers,
trevor

Prime members can get zero postage on some stuff. I am not buying them I just posted the link for information but thanks for the heads up on Australian sources.

Sound absorption is strongly dependent on absorber thickness. The Amazon panels are 25mm thick while the selbys are 45mm so should be more effective. However, these these types of wedge textured panels are primarily designed to improve listening acoustics inside a a room by reducing refections and echoes, and by scattering sound but don't contribute to sound absorption. It matters little if the noise is reflected or scattered around inside a DC enclosure so using flat acoustic absorbers will still absorb some sound. Foams help a bit as absorbers of higher frequencies but in general a dense wall enclosure material is still the most effective material.

This is an interesting website to read regarding how ineffective foams are at sound proofing.

Soundproof Foam And Acoustic Foam – Myths & Unbiased Facts – Soundproof Central

Originally Posted by BobL

Sound absorption is strongly dependent on absorber thickness. The Amazon panels are 25mm thick while the selbys are 45mm so should be more effective. However, these these types of wedge textured panels are primarily designed to improve listening acoustics inside a a room by reducing refections and echoes, and by scattering sound but don't contribute to sound absorption. It matters little if the noise is reflected or scattered around inside a DC enclosure so using flat acoustic absorbers will still absorb some sound. Foams help a bit as absorbers of higher frequencies but in general a dense wall enclosure material is still the most effective material.

This is an interesting website to read regarding how ineffective foams are at sound proofing.

Soundproof Foam And Acoustic Foam – Myths & Unbiased Facts – Soundproof Central

will the foam panels mentioned in the OP become more dense when my leaky DC fills the foam with dust?

Not much. Could always mix sawdust with epoxy to make up panels?

Originally Posted by BobL

Sound absorption is strongly dependent on absorber thickness. The Amazon panels are 25mm thick while the selbys are 45mm so should be more effective. However, these these types of wedge textured panels are primarily designed to improve listening acoustics inside a a room by reducing refections and echoes, and by scattering sound but don't contribute to sound absorption. It matters little if the noise is reflected or scattered around inside a DC enclosure so using flat acoustic absorbers will still absorb some sound. Foams help a bit as absorbers of higher frequencies but in general a dense wall enclosure material is still the most effective material.

This is an interesting website to read regarding how ineffective foams are at sound proofing.

Soundproof Foam And Acoustic Foam – Myths & Unbiased Facts – Soundproof Central

So your advice is not to use them at all Bob?

If anyone in Melbourne is wanting some sound absorbing panels I have a pallet of 600 x 600mm ones - happy to sell them by the box - from memory 10 per box and these ones can be stuck to a wall.

I'm going back quite a few years now but I once had to remove some soundproofing screens from an office. They were set up so as to divide the office space into "cubicles" for telephone operators. The screens were like those dividers you see in lots of offices, tall enough so that you couldn't look over them and wide enough to form a division between 2 desks and with a minimal gap between the screen and the floor. They were made from 2 sheets of high density MDF with a sheet of lead sandwiched between the MDF! they were, to say the least, rather heavy but they worked. They were covered in that boring grey carpet you find (or found 25 years ago) in offices everywhere. The thing is, they worked. Foam panels, egg boxes and the like stop sound wave reflection but to actually block the sound you need something thicker or more dense.
For your machine, why not try something that has worked well in places like recording studios and use 2 layers of glass or perspex with an air gap between them and with the sheets having a wider gap at the bottom than at the top? There is some mathematics involved in the dimensions and it's beyond me anyway but the last "soundproof" studio window I worked on had a 75mm space at the top and about a 150mm space at the bottom for a height of about 900mm. I doubt there was anything scientific about the measurements, that was the size of the hole and thickness of the wall we had to work with. The enclosed air space needs to be "dead", no air movement allowed.

Originally Posted by Chris Parks

So your advice is not to use them at all Bob?

Higher density foam such as found in higher end acoustic foams can help with higher frequencies but I would be wary of paying for budget foam panels to use as sound absorbers. The KPI to look for is the "bulk density" which will be clearly stated on a serious panel or otherwise can be worked out.

The overall sound absorbance is strongly density dependent with most of the cheaper foams having densities of around 20 kg/m^3 or less which makes them very ineffective. Serious acoustic foams have densities more than 10x that (ie ~250 kg/m^3) eg NBR High Density Acoustic Insulation Sheet - Foam Sales . This means a 25 mm thick 1x1m panel of these foams will weigh 6.25kg. The are usually floppy as a sleeping toddler and a bear to handle and put up against a wall. However, being non-rigid these panels do help absorb lower frequency vibrations better than light foams or even drummy harder unsupported materials.

For the budget conscious a couple of layers of thick heavy carpet or pieces of heavy foam latex mattresses will provide as much or more sound absorbance as the cheaper foams. Don't even bother with egg cartons.

Bob is right those things do from very little to F'all in terms of reducing noise. They use them in recording studios to improve the quality of the sound by eliminating echo and deflection.
For noise reduction you want mass and density, some material as thick and dense as you can. And ideally you want a gap between walls, like a box inside a box.
Not an expert, just my conclusion based on experiments with my compressor enclosure. There's a reason commercially made studio/recording boxes cost an arm and a leg.

Also vibration makes noise, make sure to put something like a rubber gym mat between your machine and the floor.

I had a computer room between 30 & 40 years ago. PDP 11/34, etc. Not my choice but some 48 x 96 x 2 (Imperial) panels were attached to the walls. These panels looked like Excelsior (soft wood shavings) piled in a heap and sprayed with some sort of epoxy. As an unscientific observer, I couldn't tell the difference with the panels installed. Impression in today's language? Meh.

At the time these panels were marketed as 'Superior Sound Suppression' panels 'and Green' for computer room walls. What can I say? They weren't. Rating wise, I would say Meh. I was told, "Have the panels cleaned regularly." Meh. I was told wear ear plugs. Then "Why the eff were these panels installed?"

The noise that we were trying to suppress was mainly computer cooling fan noise. Since then my audiologist has told me that computer fan noise is one of the most damaging sounds to human hearing. I can attest to that as in the right ear I might as well be deaf and in the left ear I can understand some speech. And the 'water holding device' batteries need to be changed about every week.

It is a shame when a four letter word needs to be replaced by a hominin description of 20 characters to keep the administrators at bay.