It's so funny that someone would think that putting a big acrylic sheet over a window will improve the sound. It will keep some of the noise out, sure, but your studio will sound like plastic. Because it is.
On the cheap it is better off using moving blankets than acrylic sheets.
Well, for cheap & quality nothing beats bonded logic...problem with blankets (well, we all use blankets sometimes) is that they act as a low pass filter.
Actually he explains principle in other part.
It is physics, and not "sound like plastic" statements.
It looks like you're new here. If you want to get involved, click one of these buttons!