Soundproof glass...how is it done?

[Mark]

I noticed while staying at the Radisson SAS at Stansted airport recently that even though the whole of one wall is made of glass that you cannot hear *anything* from outside. No aircraft despite being only a few hundred metres from the runway, no traffic and no roadworks.

The glass is a little dark, but seems to be totally soundproof. I wouldn't mind glass like this on our bedroom window since I am a light sleeper and just about anything from birds to motorbikes on the road

200m away wake me up.

How soundproof can you make glass and how is it done? I guess it would be extremely expensive?

[Guy King]

The message from Mark contains these words:

Triple glazed, I would think.

Of course a vacuum between the panes would be ideal, but they'd bow inwards and touch or break or both.

[Dave Liquorice]

Seems might be fairly relevant, I doubt that the area you where in was particulary quiet. Aircon, people, that will mask noises that would be very obvious in a really quiet room.

Motorbikes can be fing loud, particulary the high reving "sport" bikes. Outside we can hear them screaming along a road 4+ miles away down the valley.

Sound proofing relies on a few things, mass (lots of it), total sealing and layers. Ordinary domestic double glazing does a pretty good job if you want to improve on that fit another sealed frame/units double glazed window 18" or so back from the first. The large space provides a bit of cushioning between the panes of glass, two little and the air in the space doesn't compress and absorb the sound, it just transfers it to the next pane.

[Tim Lamb]

In message , Guy King writes

I don't know the answer but ISTR that the optimum distance between panes is much greater for soundproofing than for heat insulation as you have to consider the likelihood of convection increasing heat loss.

regards

>

[Dave Fawthrop]

|The message |from Mark contains these words: | |> How soundproof can you make glass and how is it done? I guess it would |> be extremely expensive? | |Triple glazed, I would think.

Perhaps quad glazed?

Glass itself transmits sound quite well. A wide gap between panes and a greater number of gaps gives better soundproofing.

[tony sayer]

In article , Tim Lamb writes

The distance does matter, in radio studios for example we sometimes use panes that are around Six to Eight inches apart as well as being angled or sloped relative to each other, but this is to improve the reflections within the studios.

Around 4 to 6 mm thickness glass is used......

[dom]

Remember it's all structural elements, not just windows, that need to be designed to supress sound.

Yes, I've also heard large gaps in DG required for soundproofing, but smaller gaps for improved thermal insulation. Obviously well fitted DG is better than single glazed sashes - but beyond that the payback may be small.

You might be better with thick curtains, thick carpets etc. to dampen sound within the room.

[Guy King]

The message from tony sayer contains these words:

I should expect having the glass sloped relative to each other would make a difference to sound transmission as well.

[John Kelly]

From experience. We once lived on a main road and once in realised that the traffic noise was just too much for us. We double glazed everywhere at the front and that was fine at night (road was quiet) but during the day was still noisy. Luckily we had very deep walls so there was a lot of space and we put a third window behind the double glazed window downstairs in our main room about 5 inches behind the double glazed unit. After this the only sounds that came through were the lorries thundering past during the day but as the house shook when they came though I don't know what would have helped remove that noise. In the end we solved the problem entirely by moving house to a cul-de-sac. I miss the old house but I don't miss the noise.

[Malcolm Stewart]

From memory, and assuming no gaps or other short-cuts for the sound waves, sound transmission across a boundary is simply related to ratio of densities of the air/glass and glass/air interfaces. So the more interfaces the better, and triple glazing will lower the sound level significantly. It's rare for there to be no sound leaking gaps in normal buildings, and the surrounding structure has to be correctly made. (Probably more difficult to get a decent audio quiet room than one for RF electrical tests, and they're not easy when >100dB of attenuation is required!).

[Phil]

Sound dampening glass is usually triple glazed, with each layer of glass a different thickness to the others to more effectively damp transmission of vibrations - each pane has different resonant frequencies.

Phil.

[adder1969]

..or the low burbling ones that neighbours leave running at 5am in the morning to warm up while they have their breakfast.

I have double glazing but much of the sounf transmission comes around the frames through the gaps. A friend had secondary glazing in his flat in addition to double glazing and it was amazing - shut the secondary glazing and you couldn't hear a thing from outside.

[Chris Hodges]

Adjusting them can help a lot with this, but trickle vents can let in quite a bit of noise even when shut.

Even heavy lined full-length curtains can make a big difference - the closer they hang against the wall the better.

Chris

[Chris Hodges]

Isn't the middle pane normally angled as well? Or is that just in recording/radio studios?

Chris

[Dave Plowman (News)]

You can get adequate insulation for most recording studio purposes - say studio to control room - with just two layers of thick glass well spaced - say about 12-18 inches. It's unlikely you'd want a window between two different studios. The above insulation allows an orchestra at full belt barely to be heard in a quiet control room. So an attenuation of probably better than 70 dB.

[Dave Liquorice]

Neighbours? Oh you mean the people living 1/2 a mile away. Can't hear them, doubt I'd hear them if they disconected the exhuast on the tractor. B-)

Just hop on and move it a further away. B-)

There shouldn't be any gaps, either in the seals or around the frames.

Properly installed double glazing should do that without the abomination of secondary glazing.

[fred]

In article , Phil writes

One of the Pilks sites gives a bit of an insight:

glass better, then DG, then DG with differing glass types (laminated), better again with increased gap between panes.

[Dave Plowman (News)]

Not for best noise insulation. Single glazing with secondary spaced to the thickness of the wall is very much better. It's also easy to get thick glass secondary glazing. I agree it's a pain, though, unless the sound insulation is important.

[Dave Liquorice]

I have my doubts, it must be a pretty close call single or secondary glazing 25dB attenuation each. Double glazing 50dB... (Guesstimated figures from experience).

Certianly our new double glazing does a fine job of keeping the sound of Tornadoes at 200' out. Most sound now appears to come through the roof and ceilings or the older windows, (4mm gap sealed unit glassware but in normal timber frames).

I'd go for good quality well gapped (as per the regs now 20mm+?) double glazing first and see how that fairs before using single with secondary. If the DG doesn't perform well enough on it's own you can still add the secondary relatively painlessly.