Choose your corner!

[HapiCmpur]

In both corners depicted in the attached drawing, we have 2 sheets of 2" thick rigid fiberglass. In Corner B, the two sheets have been stacked in the traditional manner (the Missionary Position, if you will), one right on top of the other. In Corner A, one of the sheets has been cut in half (lengthwise) so that it fits deeper into the corner, thus creating some air space between it and the outer sheet of fiberglass.

Is the additional air gap a pro or a con, and if it's a pro, is it enough of an improvement to make it worth the loss of one-fourth of the fiberglass, not to mention the hassle of the additional cutting and hanging this configuration would require?

 

[Mind Riot]

I would pick Example B. Not only is it easier to make, but if you think about it, the way the fiberglass is positioned already varies the effective air space behind the panel. At the center of the panel the air space is quite large, at the edges of the panel, the air space is only a few inches to nothing. This already makes it effective over a range of lower frequencies.

Strictly speaking, having something other than air in the space behind the panel is good, but I wouldn't break up the fiberglass to do it. I don't really have anything to back this up other than a gut feeling, but I do know that having a room treated with a lot of 2" fiberglass will not be absorbent at lower frequencies, but having a room treated with 4" will. Again, nothing but a gut feeling, but I think it would be less effective with the fiberglass separated.

For one thing, by cutting the fiberglass to fit it in the smaller corner area, you're reducing the amount of coverage. MAYBE the lower frequencies that hit both panels would still be absorbed, but what about the sound that goes through the first panel then strikes the wall on either side of the second panel because the second panel is so small? It seems to me that doing Example A would reduce the effectiveness at lower frequencies.

For the best of both worlds, I would personally do Example B and then perhaps get some bags of the fluffy fiberglass and put them in the corners behind the panels.