Editor In Chief Paul White: When we recently invited readers to contact us with ideas for new Studio SOS visits, not only did we line up several such on-site visits, but we were also greeted by several common questions, which we were able to respond to via email. One such question was how best to treat a window located to one side of the mixing position at a 'mirror point' — a place (on the side walls, the wall behind the speakers, or on the ceiling) where sound from the loudspeakers reflects directly back to the listening position if left untreated. While the usual approach to acoustics in a custom-built studio involves (among other things) placing absorbing material at the mirror points — something like mineral wool or acoustic foam — most domestic settings require that the window must remain usable, you don't get to block it out permanently! So, if you're faced with this situation, what are the options?
Ideally, where the window is to one side of the mix position, you still need something that provides the same absorption as the panel you use on the opposite wall — that way, you'll retain acoustic symmetry. But to do that might have an unacceptable impact on a dual-use room — you'd build an airtight shutter stuffed with mineral wool, and that would block off the window in a semi-permanent way.
But sometimes you just have to pragmatic, and strike an acceptable balance between what's ideal sonically and what feels comfortable to work in. An option with slightly less impact than the semi-permanent mineral wool shutter is to wedge a foam panel in the window every time you mix, though that can appear untidy. Believe it or not, a simple curtain will often help to absorb high frequencies, and the thicker the curtain the better. It's certainly a more home-friendly option!
But better still is to recognise that absorption isn't always the best option in this setting, and we've found on our home-studio travels that slatted wooden blinds (wood is better than the cheap plastic ones), set to their half-open position, seem to work pretty well. These obviously don't absorb anything, but they do tend to both scatter and deflect reflections (which can be absorbed by any absorbers you've placed elsewhere in the room), reducing the effect of first reflections interfering with the direct sound from the speakers, and thus improving the stereo image.
This type of blind is available free-hanging, and you can also get fitted shutters (either self-fit or fitted for you) with the slats mounted within a rigid frame. I fitted a set of these to my home office and they're very easy to install, as long as you send the correct dimensions for the window aperture to the company making them for you. A big advantage of shutters like these is that even when set half open, they still allow a good amount of daylight into the room. And if you really are a belt-and-braces kind of person, you can still hang a heavy curtain over the blinds to dry up the high end further. You could also place a similar blind over the absorber on the opposite mirror point to improve the acoustic symmetry.
Is this a perfect solution? Of course not. Obviously this approach does nothing to absorb mids and low frequencies. But in many domestic rooms, there can be no such thing as perfect studio acoustics, and this simple approach can still lead to a significant improvement where you have no option but to work with a window at the mirror point.