Window treatment to dampen sound?

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Tue Nov 08, 2011 11:19 pm
I'm thinking of making a window insert or cover to try and dampen some late night noise that is becoming more frequent in my neighborhood. Some of the noise is from the intentionally noisy car mufflers that are becoming more popular where I live (Seattle) and our neighborhood paper delivery person has one, some is noise from service vehicles at two business a block away (1 Gas Station, and 1 Restaurant that is becoming more popular), these are trucks deliver fuel, or taking away garbage, at very early hours (6am).

I've read about acoustic glass, but that I don't think I need that as I'm not trying to block all sound 24 hours a day, I just want to dampen or block sound during the night hours.

My windows are slightly inset, so there is room to build a snug fitting panel of some sort, and place them in clips that can hold them into place.

My questions are: has anybody here done this, and what materials did you use?

I was considering a light wood frame, with cork panels as the infill, then enclosing the entire panel in a wrap of heavy felt.

I've been doing some reading on the 'net and have seen people making large acoustic panels from rigid fiberglass and acoustic vinyl, but that might be more than I really need, and those materials might be more difficult to track down.

Has anybody had success with any other materials?

The biggest flaw I can see in my design, is that in the summer I like to have my windows open, so I'd need some other solution -- these panels will be useful only during the colder months... unless I can find a design that lets some airflow, but reduces sound flow.

Thanks in advance for your thoughts.
Wed Nov 09, 2011 10:31 pm
The Solutions section on NoiseOFF covers materials such as insulating window treatments and interior windows:

There is a product called Eclipse Noise Reducing Curtains that claims to reduce noise levels, but I am dubious of its effectiveness. That said, if anyone has had any experiences with this product, I would love to know how they would rate it.

Interior windows, specifically designed to reduce noise (CitiQuiet, Citiproof) is ideal. The windows are highly effective at reducing ambient noise (such as roadway traffic) but not as effective as a nearby car alarm or noisy motorcycles. The windows require professional installation and are very expensive.

If you go the DIY route, it will require some experimentation. You could try using the heaviest thickest curtains you can find with a vinyl backing and then sewing two or three sets together to create layers. The downside is that it will block out all light and airflow. If you find a solution that works for you, please post it here as others can learn from it.
Sun Nov 13, 2011 12:15 am
I bought a pair of the noise reducing curtains for a single window, and found that they blocked out only a small amount of ambient sound that was not bothering me in the first place. They are described as reducing noise by up to 40%. Maybe they do, but it did not seem to be the noise I hoped they would reduce, which is remote keyless entry horn honking and friends and car service drivers who honk their horns when they are picking someone up. The curtains look great, though, and I think the claim that they save on heating and cooling costs is likely true.

Years ago, I lived in an apartment with only two windows facing the street. A man would pick up someone next door early in the morning and honk his horn, and when I asked him not to, he retaliated by honking more. I bought some sound blankets used on movie sets to block out street noise, and they worked very well. There was a window facing the back, so I was able to get some natural light. I don't know if sound blankets and moving blankets are the same. With my recent noise issue, I've thought of buying more sets of noise reducing curtains and some sound blankets, and use them together with the sound blanket in the middle. But I plan to move and do not want to invest hundreds of dollars when this might not work. I've also thought about wooden shutters as a possible solution, but again, I would not want to invest that in my current apartment.

Last year I stayed at a bed and breakfast located on a busy street in Baltimore, in a room facing the street. There was a lot of keyless entry horn honking along the block, and a bus line ran along the street, and I was concerned about noise. As it turned out, every room in the house had double pane windows, and there was low key white noise from central air conditioning, so I didn't hear any street noise during the night.

SeekingSerenity, please let us know what you wind up doing, and include pictures, especially if the inserts work.
Wed Dec 07, 2011 3:52 pm
I would say that the real kind are definitely more effective then the make shift kind. I did a little research, because I am also looking for something similar. I came up with this place that sells sound blankets. What is the quality of their blankets? Does anyone know the typical cost? Thanks.
Mon Dec 12, 2011 12:48 pm
I bought sound blankets at a film production supply store twenty years ago. All of the blankets I've seen online are more expensive than anything I bought years ago and I have no idea how well they work. If you are still doing research, it might be worth it to find out if the film industry still uses these, and where sound technicians buy them.
Mon Apr 02, 2012 11:42 am
I'm going to set the record straight here.

There are three types of noise control materials, each with a different purpose.
1. Absorption - This is for echo reduction, is governed by the NRC rating, and relies on sound passing through it twice, firstly on incidence, secondly on reflection.
2. Isolation - This is designed for reducing the sound transmission between one area and another, and is governed by STC ratings.
3. Diffusion - This is designed for acoustic "tuning," and is wa-hay too complex to discuss here.

The materials designed for each are highly specialized for their intended purpose. Frequently, high-power absorption materials will do nothing to isolate noise.

What you want is to add a barrier of a different thickness and density than the window. Every material has what is called a "resonant frequency," which is a little like a color, only for sound. If you put two colored lenses, each with a different color, they will absorb more light than two lenses of the same color. The same principle applies to noise. Get a dense material (the denser the better... perhaps 1" sheet of gold!) that has a different resonant frequency than your glass.
The two factors that reduce the effectiveness of window treatments are insufficient mass and improper sealing.

STC ratings are calculated based on a complex "deficiency" schedule, in which even small leaks figure prominently. In your case, a secondary window with a polyvinylbutyl interlayer is probably worth considering. They can be opened and closed like regular windows. A 2 lb/sq. ft. barrier curtain panel could be hung from hooks during certain times of the day, too. Not sure about other manufacturers, but secondary windows from SPW have instructions for installing them yourself.

I can say one thing for certain, though. Acoustic infill panels, foam panels, and other absorption-purposed materials will do nothing for you. Nothing. Isolation takes mass. The right sound blankets for an isolation job have what's called a "barrier septum" of 1/8" thick barium-loaded vinyl sewn through the center.
Mon Apr 02, 2012 11:46 am
Also, if you're looking for airflow and isolation, it's tricky. The closest thing to doing that is an acoustical louver, which is basically a grating with absorption on the grates, which allows air through but not sound. However, getting these that actually work is a pain. There are about 8 manufacturers that actually do it correctly and actually use 3rd party testing. Good luck guessing which they are.
Tue Jan 22, 2013 6:46 am
There was a window facing the back, so I was able to get some natural light. I don't know if sound blankets and moving blankets are the same. With my recent noise issue, I've thought of buying more sets of noise reducing curtains and some sound blankets, and use them together with the sound blanket in the middle. But I plan to move and do not want to invest hundreds of dollars when this might not work.
Sun Jul 26, 2015 5:19 pm
There are a lot of great responses in this thread. I want to try to add to it.

Frequency was briefly mentioned but is perhaps one of the most important points here since people have noted that they want to block certain sounds but not all. The best way to research this topic is to learn about sound, it's spectrum of frequencies and material resonance.

A bass frequency has a longer wavelength while a high pitch sound has a shorter wavelength. I think most people here are interested in the higher pitch. ScaryBikerDude gave one of the best answers and mass does help block sound because it helps prevent all frequencies from getting through the material. If you have something heavy, it's hard to move (vibrate) it for example, but not always. Metal will conduct sound much better than concrete for example.

The reason double pane windows work is because of the layer between sheets of glass. Most high E windows fill that space with a noble gas that is less dense than air. If we could surround our houses with the vacuum of space it would be dead silent because sound (unlike electromagnetic waves) can't pass through a vacuum (no air) because it can't vibrate through the air since there is none. Since it's incredibly difficult to create a vacuum that will sustain in our windows and walls they use gases that are less dense than air so less particles to vibrate through.

Not only am I hating the noise pollution problem humans have created, but I also seek good insulation materials for energy efficiency and a sustainable house. Sound suppression and building insulation have a lot of similarities. My knowledge is still limited when it starts to get really technical, but when you want to insulate your house so that heat doesn't transmit through it (for both keeping you from losing your air conditioning in the summer or keeping the heat in during the winter), you want to find a material that has tiny air pockets inside of it. You want to reduce conduction while increasing dead (vacuum) space. I think the same thought might be applied to soundproofing though I am a little bit confused because I also just learned that some speakers are filled with insulation material to increase it's sound acoustics. I don't really know how acoustic insulation works but you certainly don't want to use it for soundproofing if it helps conduct sound through it.

Anyway, there are some thoughts to consider when researching this topic. Good luck to all!

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