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Could you please advise the simplest method to reduce low frequency noise from windows?

The problem:

  1. Somewhere outside there is a source of noise with frequency of 166 Hz. I can’t neither find nor remove it. This could be ventilation hoods on other houses, factories or something else. Let’s take this as granted.
  2. I have windows which consist of packets of 3 glasses each 4 mm of width which I can’t change.
  3. As the result there is a buzzing noise in the room in 166 Hz frequency (and I see 49 Hz as well). The noise on these frequencies about 20-25 dB higher than on other surrounding frequencies.

What I tried to do:

  1. I put shields made of expanded polyethylene about 2 cm thick and this didn’t help at all, low frequency sound passes through easily. Again, these are still windows, not good idea to cover them.
  2. I put suction cups towel holders (made of plastic) on windows, to made it harder for glass to vibrate and it helped a little bit. They are not so massive, so effect is low.

Ideas:

  1. Of course, I can buy weighty glass cubes and glue them to windows instead of suction cups towel holders, this could help bit more.
  2. I can put extra pressure on these suction cups towel holders by planks attached to window frames.

But are there any better ideas how to cancel the noise from window on the specific low frequency?

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  • $\begingroup$ suction cups would not prevent a glass pane from vibrating $\endgroup$
    – jsotola
    Feb 21, 2023 at 18:04
  • $\begingroup$ For sure they wouldn't, but they add some mass in the center of the window and (probably) change the vibration frequency so that the first or second or third vibration mode (probably) doesn't equal to the frequency of coming noise. In any case, it helps a little bit, reducing the noise for on this frequency about 5-7 dB. Not the solution, but the first step to it. Better than nothing. Maybe some help comes from the rubber used in the suction cups, as well. Somehow this addition reduces the amplitude. $\endgroup$ Feb 21, 2023 at 18:11
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    $\begingroup$ don't spend extra money ... get suction cups ... use them to attach water filled bottles to the window ... that way you can determine if glass cubes would work $\endgroup$
    – jsotola
    Feb 21, 2023 at 19:10
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    $\begingroup$ use double sided tape $\endgroup$
    – jsotola
    Feb 21, 2023 at 19:51
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    $\begingroup$ it's probable that the location of the damper object makes a difference ... vivolibero.org/esperimenti-scientifici/… $\endgroup$
    – jsotola
    Feb 21, 2023 at 19:58

2 Answers 2

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Some thoughts on your problem: have a look at the physics behind "Chladni plates" - your window pane will act as a passive speaker at 166Hz but not in a "pumping" fashion like a passive membrane in loudspeaker. Most likely, there will be a symmetrical pattern of high amplitude areas. You want to take energy away from those areas.

This is how I would go about it: use a sharpie (or washi tape) to divide the pane into a regular grid of about 8x8 in squares. Label them: A1, A2, etc. ... have a 2nd person press their finger in the center of those squares with light but equal pressure while you have your eyes closed. Note the areas where you experience the highest noise reduction. Hang your mass from the top of the window frame and then use a dampening = absorbing polymer (PUR/Sorbothane, not silicone or rubber) and wedge/glue it between the mass an the high-amplitude zone(s). Alternatively, wedge a pole-dancing pole (or a background paper holder for photo studios) between floor & ceiling in front of the window and use this as an anchor point instead of the "mass"... don't forget to seal the gaps between window & frame...

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  • $\begingroup$ Thank you for the prompt feedback. One of my initial ideas was very close expect that my plan was to attach bars to the window's frame and put wood/rubber boxes between glass and bars. The problem is that I have 2 windows with 3 glasses each, so pushing at specific places doesn't help much, since the noise comes from all glasses. I put at one "grid box" and get sound from near glass or window. Anyway, I will try as the "Plan B", since although is sounds good, it still does not sound like the "Simplest way..."; anyway, I will try. $\endgroup$ Mar 15, 2023 at 17:27
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From your troubleshooting it does sound like the window is resonating. Below is a good visualization of one potential vibration mode from the Vibration of plates Wikipedia article. The mode for your given geometry will be different but it gives you and idea of how the window can resonate.

enter image description here

Increasing the mass or stiffness at the current anti-nodes (the peaks that are moving up and down) will reduce motion in that area and change the mode of oscillation; typically to a higher frequency. If your window resonates at a higher frequency than the outside source it will reduce the transfer of that frequency into the room. Note that adding mass or stiffness at the nodes (the points which do not move) will make very little change to the resonance and not improve the situation.

One thing you could try would be to get some lengths of 5/8" aluminum towel bar that you could secure vertically along the window surface. It is a common product in many hardware stores and you can get it in longer lengths. Any stiff material will work, but condensation at the window requires low moisture absorption and corrosion resistance. Running the support(s) all the way from the top of the window to the bottom will greatly increase the stiffness in that area; essentially turning the bar into a node. To adhere it to the window I recommend using 1/2" double sided tape all the way along the length. It will be difficult to get on and off, so for initial testing, just remove a bit of the tape backer from each end to temporarily hold it in place. Then you can play around with different numbers of them and different positions. Then when you like the result, remove all the backer and stick them in place.

Good luck! Let us know how you ended up solving it.

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  • $\begingroup$ Thank you for the detailed answer. Yes, this was already mentioned by jsotola in their comment. Now I am experimenting with bottles on the double sided tape. The problem is sun; when it comes the bottles fall down; tape is not very good for glass and temperate/moisture changes. I get your idea and will use it as the "Plan B", I had the same with one difference - to mount these bars to windows frame by screws and put something "solid" between glass and bar; like small wood or rubber boxes. The drawback is windows appearance. I am still not sure that this is the "Simplest way" to solve this. $\endgroup$ Mar 15, 2023 at 17:34
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    $\begingroup$ If you are having issues with the double-stick tape failing you might try the black high temp 3m tape. I have had success using it to adhere labels to 80C pressure vessels. Also by using something stiff rather than heavy; there will be much less net force on the tape. amazon.com/dp/B093Q2BRSD $\endgroup$
    – ericnutsch
    Mar 21, 2023 at 18:03

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