Acoustic glazing

[Huge]

We're having some replacement windows and doors and my wife has got a bee in her bonnet about having "acoustic glazing" in them, in order to reduce the impact of the farm vehicles that come past our house from time to time, especially early in the morning. Other than that, it's very quiet here (we live in the middle of a farm!)

I believe this stuff is laminated glass, in order to try and reduce the rigidity and hence sound transmission of the glazing?

Has anyone ever had this stuff fitted, and does it work? The figures I've read for the level of sound reduction vary enormously, from pointless (30dB).

[Andy Burns]

My current car windscreen claims to be "acoustic" on the grounds they couldn't get an "ordinary" one last time I encountered a stone.

I don't notice any difference in the traffic sounds, but did notice an annoying barely visible pattern of dots within the screen, my brain seems to have managed to filter it out now.

[dennis]

Huge dick doesn't understand that you need a ~100mm gap for sound reduction and ~24 mm for heat loss. So fitting secondary glazing is best for sound reduction. You would think its common knowledge by now.

[Andrew]

The optimum distance between panes of glass for reducing sound is something like 8 to 12 inches, which means secondary glazing.

The optimum gap for thermal performance is about 25 mm.

Then you have the sound transmission through the frame and also the gap between the frame and the brick opening.

Also, no point having expensive sound 'reducing' windows if the walls are useless at keeping out 'sound'.

[tabbypurr]

for good sound reduction you need a large gap plus 2 different thicknesses of glass. The result is very bulky & much heavier. It's not going to be practical to fit it to a door.

Of course anyone can claim glass is 'acoustic' on the basis that all glass reduces sound to some degree.

NT

[Max Demian]

Don't you need non-parallel panes and rubber mounts?

[harry]

It sounds like you have vacuum insulated glass. The dots hold the sheets apart.

Acoustic glazing has thicker glass. Deflects less when sound waves impinge on it.

[harry]

Not so. Thicker glass or triple glazing is the norm for sound reduction these days.

[Brian Gaff]

Depends on the offending frequencies. Nothing seems to stop LF much in my experience, indeed it might be from vibrations in the house structure as when a neighbour hired a large generator or something like that and parked it in the road for a day. The lf could clearly be felt not just heard. Brian

[Huge]

The Sofitel at Heathrow T5 has treble glazing consisting of a standard looking double glazed window with secondary glazing about 8" inside that. It's the quietest hotel I've ever stayed in. You wouldn't know you were at an airport. (I like the soft close doors with felt seals, too. Wish more hotels had those.)

But I'm not after those kinds of levels of sound insulation, just that the tractors don't wake us up at 05:30. We already sleep at the back of the house.

[Rob Morley]

I thought triple glazing was the way to go, with different sized gaps.

[dennis]

It may be the norm but it doesn't work very well.

[Dave Plowman (News)]

To get decent sound insulation requires a much larger gap between the two than ordinary double glazing. More akin to secondary glazing. And the thicker the glass the better.

[Martin Brown]

I doubt that they will make enough difference to be worthwhile against the low frequency diesel engine sounds of farm tractors. And nothing you do to the windows will prevent the big farm rollers shaking the house!

It might just about make sense in the already quietest cars where space is at a premium but it is distinctly oversold.

It might well be good for 6dB or so. But you can do much better with a bigger airspace and secondary glazing if space is available. Hearing is logarithmic so you may still need a sound meter to spot the difference.

[The Natural Philosopher]

Properly sealed DG is about 20dB better than crap single glaze with draughts.

Getting much more is, as others have said, difficult and expensive:

"Anglian?s standard A rated windows provide a sound protection level of

*31dB*, helping to reduce unwanted noise. But if you require an even higher level of noise reduction - for instance you might live near a busy road, next to a railway line or under a flightpath near an airport

- you can opt for our ?Safe and Sound? range of sound reducing windows.

They offer a superb level of *36dB* sound insulation - significantly greater than our standard windows - to give you even more peace and quiet. They achieve a standard energy B rating, which can be upgraded to A for extra energy efficiency. Not only does the soundproofing keep external noise at bay, less of the sounds you make will escape through your windows. "

So what 5dB? Not a lot really compared with 31dB.

Which I assume is the difference between no window at all and an anglian DG unit.

[Dave Plowman (News)]

It makes a vast difference.

Remember The Bill? CID room had windows overlooking the road through a busy industrial estate. Original glazing - Crittal windows - meant many re-takes for traffic noise. Adding secondary glazing meant only a possible re-take in a very quiet scene.

But do remember it only works when the windows and secondary glazing is shut tight. Which wasn't so nice on a hot day.