Hello and welcome
LOL
Translate this then easy.
Two ways of doing this you can either put up plasterboard with timbre and door. Now you have two rooms one with a wider width and yet no problems with sound changing within the crazy L shaped configuration.
There fast quick and so simple! Now it’s a question of your willingness to make this doable and if there is one word I don’t like to hear, and that’s the word impossible.
So use the larger width area, I take it’s it for the home cinema correct?
And if so, matching loudspeakers a good set of matching bookshelf types for that size of volume would be quite sufficient.
Place the bookshelf matching (three-screen) loudspeakers at least 1” above a TV monitor. Build a horizontal platform that extends the front area width of the front and via placing the loudspeakers close to the edge with a downward angle will help focus the sounds directivity.
Do not place the left and right too close to the sidewalls not with a width that is over 10 feet! Mind you’re the room’s width is wider than my front room but only via a few inches.
Next plan the surround loudspeakers out for the room, if you what my personal and honest opinion the in wall ceiling designs are too costly and the results will be poor!
I don’t care what others have to say, you’ll never see this happening in a professional cinema.
So don’t waste good money when the budget is at stake!
Look around and I mean look hard for a good bookshelf type, typically from the same manufacture and stick an array of surrounds down the sidewalls with equal spacing and on the back wall this is where surrounds rightfully belong and that is how you’ll produce flying colours without compromising standards.
As for placing loudspeakers in the ceiling for a flush look, it really only works with height surrounds and only that alone. If you start installing loudspeakers in the ceiling for the on screen sounds you’ll have a disaster on your hands!
Psychoacoustics is the term used to how we perceive sound! You start placing the three-screen in the ceiling it will sound dreadful!
Anyway others will now try and give you there own personal options and opinions on this topic but I have seen this too many times before with this kind of thing, and there is only really one way to do it.