Soundproofing question

What’s a good way to reduce street noise coming through windows? I’ve done a little reading online and have found suggestions from insulating the windows (which makes them non-windows) using multiple layers of heavy drapes, using egg-cartons (where I’m not sure). Another idea I had was to use a cubicle divider, but that takes away too much of space from the room. Basically there is a large sliding glass window and on the other side of that window is a patio, and on the other side of that is a busy street. Not so much car alarms or horns, in terms of noise, but just the sound of the cars going by, and motorcycles, of course. And this room is large enough to divide up into three areas, which brings me back to the divider idea.

Egg cartons dont soundproof anything - the egg carton like texture you see in studios is about damping of reverberations/echoes (and amateurs use eggboxes largely because they misunderstand this)

Soundproofing usually consists of multiple layers of different materials with different densities (including air) - sound is absorbed or dissipated at the interfaces between layers. That’s going to be hard to do for a window without losing light and view, but additional glazing layers may help.

I’ve heard of people planting tall hedges outside of windows to lessen street noise.

You need something solid between you and the street. A thick wooden fence with no gaps would help a lot. A brick wall would be even better.

Soundproofing isn’t trivial.

By far and away the most effective thing you can do is to replace the glass in the sliding window with a sound reducing glass. This means a laminated glass, where the laminating layer forms a constrained layer damping system. However the best results are obtained with about 10mm thick glass (and the thinnest laminated you will find is 6mm.) The window may not be able accept the thicker glass, and replacing the frame with one that can can lead to serious money.

One thing to be aware of is that noise, and especially noise in the frequencies we get in road noise, need a perfectly sealing window. The noise can leak in though the slightest leak. So this means the window must have good seals in good condition. That is probably something that you should check right away.

In an extreme you can double glaze with laminated glass, but this means two layers of 10mm glass, and instantly means commercial level window framing. Curiously, for sound insulation the panes should be spaced a far apart as possible - whereas for heat insulation they should be much closer.

Heavy window drapes can help. You need mass to damp the sound. Some of the heavy blockout fabrics are not too bad. But you do need to layer the system. Also it all needs to fit well, and remember the bit about leakage.

A very effective material is barium loaded vinyl, although using this to make a curtain for the window would be difficult.

Once the sound in inside you have a whole lot of other problems. You can’t really control it much with things like dividers. The wavelengths are much too long. However good damping in the room will reduce the level of sound - most of the sound you hear will have reflected off multiple surfaces, and keeping the amount of reverberent energy down is always going to help. Soft furnishings are good. Be aware however, low frequencies are very difficult to adsorb. The common acoustic treatments you see are next to useless here, and can actually make the perceived sound worse. But hard floors, sparse modern furniture, hard walls and ceiling, will all make for an unpleasant acoustic environment that will exacerbate the intrusive nature of the road noise.

Thanks. I’m thinking curtains inside and another layer outside, like exterior blinds for the patio, at this point. It’s a rental so I can’t just replace the window.

Did you recently move there? Or has this bugged you for years?

One of the big problems with sound insulation is that it takes a lot of work to reduce noise by 6dB. Now, “twice as loud” is subjective, but it’s somewhere between 6dB and 10dB. So, reducing by 6dB makes noise half as loud, which is significant.

But for sleeping, unless the noise is just over the nuisance threshold, 6dB isn’t that big a difference, simply because our ears and minds are so good at “auto leveling”.

My suggestions are:

a) Give it a year or so, assuming you’re new to the location. You’ll adjust. When we moved from the country where we’d been living for 10 years to a city residential area, I thought I was going to go nuts, but within a short while I acclimated.

b) Build a big brick or cement block wall between the patio and the street. (Oops, rental. Sorry.)

c) Move.

The curtains are worth a try, but don’t expect too much. Use the heaviest fabric that you can.

What about depleted uranium?


Used to live on a streetcar line.

The term you are looking for is STC - Sound Transmission (something). The higher the number, the more sound it absorbs.

First: Carpet. Heavy carpet on high-density foam. I don’t care if you love hardwood - the house had hardwood when I bought it. The carpet knocked it down by a factor of 50%. Hardwwod acts as a sound board.

Now you want as much soft and absorbent material between your ears and the street - heavy drapes and tapestries are good starts.

When it gets to the window: STC 45 (a mile from departure end of the runway at the big international-type noise) windows 3’ wide by 5’ high (old house) cost $500 each, special order through Home Depot. These are tripe glazed monstrosities.

Years ago, serious soundproofing was done by adding a continuous sheet of lead in the walls. There is now a 1 pound/sq ft product intended as a direct replacement for lead sheet.
Note that the mfgr states: a 3"x3" hole in a sheet reduces effectiveness by (either 50 or 90%).
This is a pro-install product, with its special sealant for the (over-lapping) joints between sheets.

I mention this stuff simply to point out how important that window is to the problem.

Sum: lots of absorbent materials, and no gaps in them.

Yup. That is the barium loaded vinyl sheet. It comes in a range of weights depending upon the manufacturer. It has all sorts of interesting uses in sound control. But as a sheet inside a wall is the most common. What matters is that it is both heavy but also that it dissipates energy as it flexes. (Depleted uranium is too stiff to work well.)