Best acoustic walls

[PeterW]

We have a downstairs layout that is being planned currently but I want to limit the external sound. Although we are next to a road we get one or two cars an hour at most. The main noise is the main line railway about 45 yds from the house but again the train numbers are surprisingly low. I'm on site now and the birds are making more noise ..!

 

 Anyway .. the study will also be the spare room so I'm looking for ways to reduce sound and I've got options. The inner of the external quadruple leaf brick (yep..! 4 skins..!) will have 75mm Kingspan for thermal reasons. I've then got a utility space and I'm thinking that the wall between utility and study can either be block or studwork but what is best..?! This is low frequency noise and I'm erring on using block to give more mass and stop vibration

 

Thoughts ..?

[Jeremy Harris]

Block will be pretty good at keeping out airborne noise, but not so good at ground-transmitted low frequency "noise", so it really depends on how much of the railway noise is airborne and how much is vibration transmitted through the ground.  Reducing sound from vibrations transmitted through the ground really needs flexible isolation, with the isolated structure having enough mass to ensure that it has a resonant frequency that's a lot lower than the lowest transmitted frequency, which may not be that easy to build.  A surprising level of sound comes in through tiny air gaps, too, I've found.

 

I can say that blown cellulose insulation between two, fairly well isolated, stud walls seems to be incredibly good at reducing external sound penetration, something that I wasn't expecting.  Our new house is, if anything, too well sound insulated, as you can't hear anything going on outside, not even a Chinook flying overhead, when the doors and windows are closed and latched.  Whenever I have heard a sound inside it's always been because a door has been closed, but not latched tight to its seals.  It means that even a truck coming up the drive can't be heard inside, let alone a car.

 

If you go for a stud wall, then I'd be inclined to fill it with dense insulation and try to isolate the skins on either side.  If you go for block, then it will probably give better airborne noise reduction, but may be a bit worse at reducing structurally transmitted sound.  An example of this is the way sound like a light switch click may well be clearly audible from the other side of a block wall - something that's noticeable in our old house, that has block inner walls, but isn't noticeable in the new house that has acoustically insulated standard stud walls.

 

 

[PeterW]

Thanks for that comprehensive answer @JSHarris.!

 

I am thinking that blockwork may be quicker as I have the guys on site and although I can't isolate the ground noise the trains are so infrequent that it's going to be a compromise anyway 

 

thanks

 

Peter

[Ferdinand]

I would slightly differ from Jeremy in that I would fill a stud wall with rockwool if not able to isolate the faces. I did that with a couple of treatment rooms in the gym I have been talking about, and it seems OK.

 

It does however depend on the nature of the noise as we all know. We needed to isolate from gym music and talking.

 

If you have the guys, then perhaps go with the blockwork. Can you choose different types of block for different types of noise?

 

I suspect that nothing will isolate you from the ground-propagated noise, short of a modest  earthquake-style solution. For the gym the best solution to keep the floor below isolated from dropping heavy weights was concrete platforms mounted on tuned dampers, which was almost a recording studio style isolation. 

 

Ferdinands

Edited March 12, 2017 by Ferdinand

[Ferdinand]

Hmmm. Off the wall, maybe but,,,

 

Can you do anything with outside groundworks and eg trenches or hahas?

 

Does ground sound transmit through a deep moat or a Leca or tyre-shreddings filled French Drain on that side around the foundations, or on the boundary? Depends on the sound path.

 

I don't know the answer.

 

Summary that focuses on above ground things in the garden.

https://www.fhwa.dot.gov/environment/noise/noise_compatible_planning/federal_approach/audible_landscape/al04.cfm

 

Ferdinand

Edited March 12, 2017 by Ferdinand

[daiking]

Earplugs would be cheaper

[Liam]

On 3/11/2017 at 7:29 PM, JSHarris said:

Block will be pretty good at keeping out airborne noise, but not so good at ground-transmitted low frequency "noise", so it really depends on how much of the railway noise is airborne and how much is vibration transmitted through the ground.  Reducing sound from vibrations transmitted through the ground really needs flexible isolation, with the isolated structure having enough mass to ensure that it has a resonant frequency that's a lot lower than the lowest transmitted frequency, which may not be that easy to build.  A surprising level of sound comes in through tiny air gaps, too, I've found.

 

I can say that blown cellulose insulation between two, fairly well isolated, stud walls seems to be incredibly good at reducing external sound penetration, something that I wasn't expecting.  Our new house is, if anything, too well sound insulated, as you can't hear anything going on outside, not even a Chinook flying overhead, when the doors and windows are closed and latched.  Whenever I have heard a sound inside it's always been because a door has been closed, but not latched tight to its seals.  It means that even a truck coming up the drive can't be heard inside, let alone a car.

 

If you go for a stud wall, then I'd be inclined to fill it with dense insulation and try to isolate the skins on either side.  If you go for block, then it will probably give better airborne noise reduction, but may be a bit worse at reducing structurally transmitted sound.  An example of this is the way sound like a light switch click may well be clearly audible from the other side of a block wall - something that's noticeable in our old house, that has block inner walls, but isn't noticeable in the new house that has acoustically insulated standard stud walls.

 

 

 

Thanks a lot, this information really turned out to be useful to me. The other day I am going to work with the walls.