Blocking air-conditioner hum through single window

  • Thread starter Thread starter willmarshall
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W

willmarshall

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Hey guys,

I'm in the process of building a new home studio / mixing room, and I'm trying to reduce background noise.

I live in a quiet, pre-war brick apartment building in Brooklyn. The walls are 14" brick, and the windows are all brand-new, double-glazed, tightly fitted beautiful things. I have no traffic or street noise, and no bleed inside the building, since the internal walls are all brick.

There's only one problem: my neighbours have an old air conditioning unit in the light well outside my studio. The windows block most of the noise, but there's a peak at 260hz coming through the window at about 39dba. The sound bleed is totally localised to the window - there are no other gaps, vents, etc in the wall whatsoever.

I'm researching and pricing up my options for further sealing the window. So far my options are:

  1. Creating a DIY window plug (blocks light, will presumably seal the window)
  2. Buying a fitted Indows window-insert (expensive, but effective?)
  3. Fancy soundproofing curtains from Residential Acoustics
  4. DIY-building an acrylic internal second window - basically a DIY Indows insert

Making a DIY window plug is my "nuclear" option, but I'd rather do something more elegant. My cheapest option is curtain (I can use their standard size), but I'm not sure how well it will actually work.

Does anyone have a sense of how well each of these options is likely to perform?

Thanks,
-W
 
My vote goes for the DIY plug. 2 or 4 inch thick OC703 cut to the shape of the window and covered in fabric.

At 39dB, I think it's not so loud. I used to have a window unit permanently mounted through the wall of my studio. This is Texas, you need a/c. That thing was loud, so I would turn it off when tracking with a mic, but sometimes I would forget. I'd go back to listen to my vocal tracks and I could hear it in the audio, but it wasn't bad. When the vocal tracks were mixed in with the rest of the rock-band instruments, I couldn't hear it at all.

With a DIY plug and a cardioid mic you should be good to go. Point the null section of the mic towards the window.
 
Might be a combination of air borne/structure borne noise so offer to resiliently mount neighbours A/C.
Airspace with another layer of glazing helps also.

Gary

stc_table_sm.webp
 
First I’d try a piece of plexiglas cut to fit with a good weatherstripping seal. A set of heavy “blocking” drapes that are designed for light on top of that. It’s what I have and I’ve got poorly fit double pane windows with the neighbor’s a/c and our own pool pump to contend with.

The final thing is to set up your cardioid mic so that its back is aimed at the window. Room treatment behind you prevents whatever little slips in from bouncing off the back wall into the mic.

If it’s not enough you can pop out the plexiglas and stuff the space with some rock wool.
 
I would use some kind of dense solid boundary mounted with some isolation. Absorption on the side facing out would be good.
 
Plug would be the best option, but if you still want light you could try something like this removable double glaze This link is to the Australian product but I am sure there would be a US supplier.

The worry is that 260Hz is quite low and the lower the frequency the harder it is to block.

Alan
 
willmarshall said:
...my neighbours have an old air conditioning unit in the light well outside my studio. The windows block most of the noise, but there's a peak at 260hz coming through the window at about 39dba.
Click to expand...

WTF are they running an AC unit for at this time of year?! :D ;)

You would think it would be off for at least 8 months of the year...and then the other 3-4, stuff the window, as others have mentioned.

Hey...offer to buy them one of the newer low-noise units. :)
 
witzendoz said:
We do run ours for heating and cooling. :)

Alan
Click to expand...

Well yeah, if they are designed for both cooling and heat...but if it's just an AC unit, it's not going to be run 8 months of the year here in the NE.
 
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