Marigo dots will do very little/nothing to help with the window.....lows travel through them like they were open.....highs get reflected right back at ya. My house has great walls of glass windows....I use drapes recommended by the decorator....they look nice but do some, but little to perfect the room acoustically. Sometimes you go for the look, sometimes for the sound.....rarely can they be combined.
Please comment on your experience with Plantation shutters. Yes they look great,
but do they act as good sound diffusers over windows? Has anyone noticed they improved the sound in a room with windows? I am thinking they may do a good job when tilted, but not fully closed. Perhaps even better than 2 inch wide standard shades?