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Sounds Of Science - SOFSCI - Mirror Method

The good reflections are the ones that comes after the first-hand ones and those should remain.

The Mirror Method

Having positioned the speakers and the sofa (sweet spot) in the best possible way we are now ready to deal with actual room acoustics. This is quite easily done and the first thing to think about is the firsthand reflections, which are the reflections that reach you immediately after the direct sound. These reflections are bad because our brains, although fantastic as they are, are not able to differentiate them from the "true" sound and thus the result ends up being unclear and muddled - not crisp. What you do not want to do is cover all of the walls with absorbers because then you actually remove the good echoes or reflections, the ones that produce a "roomy" feeling. The good reflections are the ones that comes after the first-hand ones and those should remain. "1" and "2" in the image to the right (click on it for larger image) are typical areas of firsthand reflections. Number "3" is a good spot for added broadband bass absorbers.


So how to find the firsthand reflections? If you ask a friend to take a mirror and place it on the wall beside one of the speakers in your general height (while you are sitting down). Then he/she walks slowly towards you while sliding the mirror along the wall - when you see the first speaker in the mirror you have found spot one and when you see the other you have found spot two. Make sure your friend marks these spots on the wall and then you do the same on the other wall. These spots are then treated with absorbing material, at least 18" (50 cm) on each side and above/below of every trouble spot. This same method can be used to find the firsthand reflections both on the floor between you and the speakers and in the roof. These areas should be treated as well and when it comes to the ceiling you can hang SOFSCI panels quite easily there as well. Maybe with a nice cloud image or similar?
If your sofa is positioned close to a back wall, as in the image, then this is an area you should do the same with, which basically means you should put absorbers behind your head. A big bookshelf with different sized books works magic here as well, because they diffuse the reflections.

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