Sound Proofing Advice

[Rick]

I used this stuff in my sound room -

http://www.insulation.com.au/content/upload/FI_DS_FI32%20SemiRigid(2).pdf

Took a while to track it down, but the results were worth it.

Has very good specs and is cheap enough.

It can come with a black tissue face too if needed, which is what I got.

Mine was 100mm thick by 1200 x 2400, from memory around $60 per sheet.

Works extremely well, I have my entire ceiling and front wall covered, all with a 100mm air gap.

My room needs very little in the way of corner trapping, but will still be getting some in the way of f/glass filled columns.

To the OP, it's almost impossible to over treat a room, but almost all rooms are under treated.

[Peter_F]

Hi Rick, have got any pic's you can post?

Cheers, flemo.

[Paul Spencer]

Ken,

Firstly, you can't separate your room from the speakers - there is a synergy between them that is by far the most important in your sound system. You must consider them together!

Given that your room is small and very solid, you have a few challenging problems.

Firstly, the bass - room modes will be nasty and you don't really have the space for bass traps. The ideal compromise is to install plasterboard sheets on furring channels over all brick surfaces - the walls will then act as bass traps and give some bass damping. I would then use multiple small bass sources, with measurements and eq to get a smooth in room bass response. If you don't do some acoustic treatment for the bass first, this may prove very difficult.

Secondly, a small room can quickly become "dead and lifeless" when treated with aborption, and diffusers are difficult to place in a small room without placing you in the nearfield region where diffusers become confusers!

Keep this in mind - there is a relationship between the livenss of a room and it's size. Commercial cinemas need heavy treatment because of their size, or they would have massive problems with echo and reverb. The same treatment in a small room isn't so appealing - it will be much more dead. Why do people like the acoustics of their bathrooms for singing? It's small yet live. The extreme opposite is an anechoic chamber. It's important to get a balance.

One common approach is to use small speakers with wide dispersion placed in a room with a large amount of absorbers. Essentially this is like lighting a room with candles, then making the walls black to absorb the light! A better approach IMO is to design speakers with controlled directivity and a smooth response at all angles. In this case, much more moderate treatment is necessary (and even preferable). It's unfortunate that most speakers don't really address these issues.

One of the key issues of concern are early reflections, in particular those within the first 10ms time window. In other words, any sound that has a path difference to the direct sound of less than 3.4m can be considered an early reflection. In a small room this is the first reflection off every single wall!

It is a problem because they mess with the brain's localisation of sounds. Longer delays create ambience without damaging imaging. So you can do two things with these reflections - absorb or diffuse. Absorb and you can quickly deaden the room. Diffusion keeps the energy in the room by sends the sound around the room causing a longer delay.

[HAroldus]

Hi People

I run recording studios for 30+ years, have built about a dozen studios and mastering rooms and an currently treating a handful of ridiculously echoey church halls around Melbourne. My most used material for wide band resonance control is custom made hollow filbre batts available in 3.6M wide x however long at 32 -36 Kg/M3 which I find is better than the heavier ones I have used before ( i.e. 48Kg)

For example a recent job reduced a church hall from 3.6sec to 1.2 sec T60 and increased the intelligibility radius from 1.5M to 2.8 using only 42M2 of material on a total surface area of 780M2.

The previously unusable hall is now sought after for all sorts of live music from a capella to funk. You can hear every word from one end to the other.

The way it works financially is I get a few orders together and then get a few hundred kilos made, and distibute them immediately. Economy of scale. Good sound to the people.

And the bottom line?

Cost is around $15/SqM - anyone want some?

(I am about to have a load made for a job in the next two weeks)

[daedalus]

i heard some materials are hazardous for health (eg fiberglass). is the accoustica one or http://www.insulation.com.au/content/upload/FI_DS_FI32%20SemiRigid%282%29.pdf a health hazard?

[Paul Spencer]

Simon, fibreglass has tiny little fibres and if you get them on your skin, it's a huge irritation. I've handled it before and to be honest I was a bit slack and ended up with some annoying itches. Usually it comes out in the shower. I think the main issue is skin irritation, but perhaps if you breathe it in then you could have a problem. Look it up and you might find out more. Handling one bag is one thing. Handling them every day as an installer can turn a minor issue into a major one. You probably won't die after handling a few batts. That's just my hunch.

[Guest Drizzt]

Try having fibre class on your eye lids ... its not fun

During uni I worked casually in some factories and was not aware of fibre glass at that stage. I know now !!!!

Simon, fibreglass has tiny little fibres and if you get them on your skin, it's a huge irritation. I've handled it before and to be honest I was a bit slack and ended up with some annoying itches. Usually it comes out in the shower. I think the main issue is skin irritation, but perhaps if you breathe it in then you could have a problem. Look it up and you might find out more. Handling one bag is one thing. Handling them every day as an installer can turn a minor issue into a major one. You probably won't die after handling a few batts. That's just my hunch.

[Keith_W]

I think the main issue is skin irritation, but perhaps if you breathe it in then you could have a problem.

That is correct Paul, fibreglass is associated with Silicone Pneumoconiosis. The little fibreglass shards are not digestible by enzymatic action so the body forms little scar nodules around each fragment. The long term consequence is lung disease.

[Paul Spencer]

Cripes! Don't listen to me then. Avoid the evil batts!

[Ted White]

I often wonder if Fiberglass will go the way of asbestos.

[Guest Peter the Greek]

I often wonder if Fiberglass will go the way of asbestos.

The interesting thing about asbestos is its not actually the asbestos fibres that are damaging, they carry ferric iron particles that do all the damage, so the asbestos is a delivery mechanism, straight ot the lungs unfortunately.....the most efective way to treat this is via high strangth anti-oxidants.......ascorbate/vitamin C, coupled with some stuff called methyl sulfonyl methane to rid the asbestos particles

Now I am not as familiar with fibreglass, but take say rockwool, which is made from iron ore blast furnace slag....is it going to carry similar nasties? not sure

Those scar nodules keith is referring to - picture inhaling tiny, unseen, bits of fibreglass - if you've got it in your house your going to suffer from this.....we do unfortunately - the glass fibres act as thousands of little knives that get into your lungs and cut it to bits......in a microscopic sense anyway........but then there is general air contaminants etc etc etc, solution? move to New Zealand and live in a log cabin

Edited September 14, 2010 by Peter the Greek

[daedalus]

Accoustica HD Batts looks good, and not too expensive too http://www.acoustica.com.au/hdbatts.html

it says "HD sound insulation batts are made from non-irritant polyester which is dust free and won't cause any skin or other irritations."

just want to confirm polyester isnt like fiberglass and wont cause the same problems (skin irritant and lung problems)?

i dont care how good fiberglass is, its not worth the risk!

[Guest Willow]

The interesting thing about asbestos is its not actually the asbestos fibres that are damaging, they carry ferric iron particles that do all the damage, so the asbestos is a delivery mechanism, straight ot the lungs unfortunately.....the most efective way to treat this is via high strangth anti-oxidants.......ascorbate/vitamin C, coupled with some stuff called methyl sulfonyl methane to rid the asbestos particles

And the other interesting fact is some of us are drinking Asbestos from time to time.

[Ted White]

Very interesting info about the Iron aspect of asbestos. I always assumed it was the fiber itself, etc...

[AnthonyG]

Couple of points.

Firstly, the post that linked to Bob Golds page with absorption coefficients for Autex Polyester absorption batts - almost all of that Autex data is Opinions. The actual test data are the products shown with the asterisk next to them - all the others are "predicted". This is clearly explained in the relevant Autex brochure. I've sent Bob a couple of messages about this but didn't receive any reply; it is possible the page is "as is" and is no longer updated.

Secondly, Glasswool and Rockwool are made using a so-called "biosoluble" recipe, and have been in Australia for probably 20 years or more. The way it has been explained to me is that biosoluble fibres will dissolve in human tissue within 2-3 days. The previous recipe for Glasswool and Rockwool took up to 30 days. Asbestos fibres took over 500 days. In the 70s/80s, Glasswool was classified as "potentially carcinogenic". This was on the basis of injecting fibres directly into the lungs of lab rodents. In Australia, Building Unions were very anti-Glasswool as a result. However, more relevant testing has found no effects from airborne fibres, neither with lab rodents nor with workers in the industry. Hence, the Australian Unions relented in the 90s and allowed Glasswool back on Union building sites, although not until after Polyester batts had staked a foothold in the market. Glasswool is certainly alkaline and an irritant, plus the fibres can stick in the skin. Supposedly, the Knauf Insulation is "super soft" but apparently it is not made in "audio grade" only thermally rated batts which are generally 7-12kg/m^3. I have seen no reference to asbestosis or other asbestos-related lung diseases being caused by ferric iron as mentioned in the post above

[Guest Peter the Greek]

I have seen no reference to asbestosis or other asbestos-related lung diseases being caused by ferric iron as mentioned in the post above

Perhaps you might want to look into before making wide reaching statements and perhaps back that up with appropriate qualifications which imply a certain level of specialty on the topic

Refer Sundius and Bygden 1937 and Berger 1933 - where the asbestos body was seen to be coated in proteins and iron. This has been known for a long, long time.

Kamp et al (1992) showed that the iron content of the asbestos fibers play an important role in the creation of hydroxl radicals, which result in significant lung trauma