I just moved to NYC and I have a window unit like this: window unit

The foldable frame around either side lets in a considerable amount of outside noise; it's just as if the window was open. In fact, I'd swear it amplifies outdoor noise, perhaps through the AC unit itself. Quite hard to get some sleep.

Is there a way to better insulate against the noise?


2 Answers 2


You may want to make a trip to the big box store and purchase a piece of high density foam insulation board. You should be able to find materials that are colored pink or blue that comes in 1" or 2" thicknesses.

Carefully cut pieces that will fit between the window bottom, side wall and the inward protruding part of the AC unit. If cut correctly you should be able to push the foam material into place with a nice friction fit all around right over those pleated side fillers.

You could also investigate the possibility of cutting a piece that would push in under the AC unit.

It is not clear if a piece would be needed across the top as it is not obvious from the picture if the top area lets in noise to the same degree that the flimsy side pleated panels.

Lastly there is the issue of possible sound coming right in through the AC unit itself. It that is the case this is clearly an issue when the AC unit is off and not in use. So in that case make a cover out of the foam board to put in front of the AC unit when it is not in use. Remove cover to use AC when it's noise probably fully exceeds what external noise that would come through the unit.


The key will be to a) block all air paths, and b) have rigid barriers rather than flexible barriers. So, those pleated plastic barriers must be supplemented, if not replaced.

Ideally, you should remove the AC unit (don't drop it out the window!), remove the plastic barriers and frames, and then reinstall the AC unit with 1/2" or thicker plywood on either side. Make sure there is no path for air past the unit, as that's also a great way for sound to get in (use caulk or foam tape to seal the edges of the plywood).

If you can't remove the AC unit (or don't feel safe doing so), then add a layer of plywood to each of the side barriers. Again, seal as well as you can around the plywood. It may be useful to cut the plywood larger than the real opening so that you can seal its back to the edges of the opening.

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