@milpai - One thing I have tried tried worked very well in a couple of very different rooms is a vinyl blind behind the listening position.
It is fastened at ceiling height an extends down between 15"-18"
You could simply use a piece of vinyl and pin it too the wall behind the listening chair each side of the dropped ceiling section
The best vinyl can be acquired from those companies that make signs - it is about 1mm thick and very flexible.
I used a vinyl blind because I thought the window that was behind my listening position was the issue, but after it was installed I realized it was not the window, but the reflections at the ceiling causing my problems
Regards
It is fastened at ceiling height an extends down between 15"-18"
You could simply use a piece of vinyl and pin it too the wall behind the listening chair each side of the dropped ceiling section
The best vinyl can be acquired from those companies that make signs - it is about 1mm thick and very flexible.
I used a vinyl blind because I thought the window that was behind my listening position was the issue, but after it was installed I realized it was not the window, but the reflections at the ceiling causing my problems
Regards