Straw Bails For Sound Proofing

[Pies]

Hi

After a few long weeks and a number of buildings falling through I have finally found a new space in the top of a barn at a local farm.

When talking through my building plans the landlord suggested using straw bails as insulation instead of rock wool.

The more I think about it straw has a good amount of mass and I think it will have good absorption properties so that combined with a double layer of soundbloc plaster board and skimmed could be the way to go I think?


Does anyone have any thoughts on this and how sound proof it would be, I know the rockwool and plasterboard construction I was looking at would of taken a drum kit down for 90dB to about 60dB which wasnt enough of a reduction.

This year at Glasto Festival they have got a studio constructed out of straw and to keep out the noise from the punters I'm assuming they have done their homework and figured out it has some good sound absorption properties.

Cowshed Studio Glastonbury

I need to also mention there is a sandblaster on the farm so I am looking to keep out as much noise as possible.



Thanks
Ow

[RusRant]

Sounds like a major fire hazard. But otherwise, can't help ya.

[rogerbrain]

probably work great... but get a no smokin' sign.

[Pies]

I have done some research into the fire hazard side of things and straw is actually no more flammable than wooden walls and stud frames. When rendered it is as flammable as brick, so that isn't going to be a problem.

[avare]

What will you do with the other side of the bales? First and foremost though, how much sound isolation do you need?

Andre

[DanDan]

Insulation is not Isolation.
Very roughly one might get a 3dB decrease in sound with 1 metre of fibre.
Soundproof ish walls are a system. Mass layer, airgap damped by fibre, mass layer.

DD

[Pies]

The studio is in a barn so there is brick wall already,
then I'm thinking a stud wall of standard plaster board with a small air gap between brick and plasterboard. Then bales up against that stud with another stud wall in front of the bales double layered with soundblock plaster board and skimmed.

The ceiling is going to have to be filled with rock wool and then double boarded with plasterboard.

I'm looking to reduce sound in and out as much as possible on a budget.


Thanks
Ow

[avare]

Originally Posted by Pies

I'm looking to reduce sound in and out as much as possible on a budget.

No disrespect intended, but "as much as possible" is meaningless. If it is more than you need, you will spending money needlessly. If it not how much you need, you will have wasted money.

Get numbers. This is for your benefit.

Andre

[DanDan]

Listen to Andre. Play pink noise inside, loud. Measure outside. And vice versa. Figure out what sort of Transmission loss you really need.
Forget the bales. Do a stud wall with as big a gap as is possible/reasonable. Fill the gap lightly with light fibre. Make sure the studs are not at all attached to the brick wall. Fill any gaps in the brickwork/pointing.
DIY Domestic Wall Soundproofing

Lightly, DD

[Pies]

Its needs to be sound tight but I know in reality this isn't possible on my budget so as I say as much as possible.

I can afford the design I have described so which is at the top end of my budget. This leaves me with about 20% left over but that will get eaten into if any of my other builds are anything to go buy.

If we say a drum kit is 90dB then I would looking at reducing that sound by at least half if not 2 thirds.



Thanks
Ow

[Pies]

Everything I have read so far points towards bales having far better sound proofing properties than rock wool which is why I was considering it.

What I'm looking for is someone who may have used these in a project in the past?
People can say use rock wool all day but if they have never used bales how can they compare the two
and comment on which will be the most viable material to use?

I'm not trying to disrespect anyone either as you all have a much greater knowledge in the field than I do
but trying to working out of the bales will be suitable or wether to just stick to plain old rock wool
I'm into the ecological side of using bales also

[DanDan]

Pies if I may exaggerate a little in an effort to convince you.
Rockwool and other fibres have little or no soundproofing effect.
Also a three leaf system is often less effective than two.
Also, I would say 110-120 dB SPL for a drumkit.
DD

[avare]

Originally Posted by Pies

Everything I have read so far points towards bales having far better sound proofing properties than rock wool which is why I was considering it.

What I'm looking for is someone who may have used these in a project in the past?
People can say use rock wool all day but if they have never used bales how can they compare the two
and comment on which will be the most viable material to use?

I'm not trying to disrespect anyone either as you all have a much greater knowledge in the field than I do
but trying to working out of the bales will be suitable or wether to just stick to plain old rock wool
I'm into the ecological side of using bales also

You appear to be convincing yourself. Bales of hay will be worse than rockwool in walls because it is denser. This means it conduct sounds, particularly low frequencies better than rockwool. If you have done research, the leaf-hay bale-leaf will act like one leaf acoustically.

Knowledgable people compare the 2 using physics.

Regardless, you have not quantified how much isolation you need. Dan detailed a method to do that.

Trying to help,
Andre

[Pies]

Ok so just adding more layers isn't going to reduce the sound further?
It thought this would as its more mass for the sound to get through.

As I have already explained really I need the space to be sound tight but my budget is £5000 so I know that's impossible.

So what I'm looking for is the most isolation I can gain for the amount of money I have. So taking measurements is irrelevant as this is the space I have and that is the amount of money I have left to throw at it.

[DanDan]

Ok so just adding more layers isn't going to reduce the sound further?

Correct. Almost anything you think intuitively about acoustics is quite likely to be wrong.

Three or more layers with airgaps, damped or not, is a multi leaf system.
Unpredictable, and broadly speaking, not as good in performance at LF as two leaves.

The most cost effective way to do your job is an isolated stud structure. Check out the steel option. An airgap filled with light fibre. Denser is not better as Andre has explained. This fibre is there to dampen resonance in the gap, not to stop sound. Extra layers of plasterboard are well worth doing for cheap extra mass. Three layers is good. Note these three layers are screwed together, they are one heavier one, not three.

DD

[ksandvik]

Constant dust in the air so hopefully none of you are allergic, it would be very painful to be in such a room.

PS: I was born and raised on a farm.

[Pies]

thanks for the info I will take a look at just having the one cavity then with rock wool and triple boarding and price that up as an option.

As I say I'm not asking for miracles just looking for the most effective way to spend my money

Constant dust in the air so hopefully none of you are allergic, it would be very painful to be in such a room.

PS: I was born and raised on a farm.

I don't know what you are going on about or getting at?
I have always had my studios on farms and never had any problems
along with many other studio owners,
your comment has no relevance to my questions


thanks
Ow

[bobsandifer]

Your control room cow will be much happier. It will not make much of a difference to the chickens.

[ritelec]

Originally Posted by Pies

t
I don't know what you are going on about or getting at?
I have always had my studios on farms and never had any problems
along with many other studio owners,
your comment has no relevance to my questions


thanks
Ow

wow........it is relevant or something to think about.


My 2 cents...................fill it with hay, that's what you want to hear and are going to do anyway.

[Pies]

I was referring the the dust statement not anything to do with the advice on sound proofing.

If you have a read of my last post you'll see I'm gonna have a look at other options also and I have taken into account that the 3 leaf design is going to be as good as 2 leaf design.

If I was set on the bales the I wouldn't have bothered posting on here to get other people's opinions.

[ritelec]

You might want to consider salted hay....keeps the bugs down.

[DCtoDaylight]

Originally Posted by DanDan

Almost anything you think intuitively about acoustics is quite likely to be wrong.

DD

Don't mean to hijack the thread, but ***thank you*** for saying this, Dan! I've been recording for almost three decades now, and I've worked for most of my adult life in fields that have a higher-than-average degree of technical complexity, but getting the acoustics of my new studio room in line has been a humbling process. This makes me feel better!

Thanks to you and the other Learned Ones for all the knowledge you share here - it's a tremendous help.

[Sebg]

Not directly applicable to your situation but I have always wanted to refer to this paper:

"An Innovative Use of Hay Bales to Provide Ventilation Fan Noise Control", Dick Benbow, Acoustic Australia

www.acoustics.asn.au/journal/Vol25No3.pdf

[DanDan]

That is interesting Seb.
Perhaps bales of hay do work to some extent as a stand alone barrier. They do have some mass and density. However, as a damping mechanism in a MSM system, I expect they would have a negative effect, as Andre described.

There has been a charity motor racing event staged near me.
Acoustic consultants did a test which established levels of 74dB at nearby houses. They suggested a solution. A barrier of 3 artics, wth the gaps between and underneath sealed with straw bales. They calculated a loss of 21dB for this barrier. I measured 76dB at the houses.

DD