The best room upgrade: $2250

I live in hot as hell Sunny South Florida. My house is open beam ceiling (no attic). Upstairs without air conditioning on is 95* +!

I finally got around to getting the roof Siliconed to knock down the heat and UVs= lower electric bill. What I didn't know was the impact it would make, quieting my listening/TV room. For the first time in 25 years, no traffic noise from nearby I-95 and I-595!!! And when I turned on the TV the sound was relaxed, not echoing in the room. I haven't yet put the stereo on, but will later today
Glad I did this before my Voyager amp arrives- any day now. I need to get a handle on how this changes the sound before I put in the system
And so the silicone is on the outside of the roof. I certainly can see the thermal and acoustic advantages of incoming heat and sound. That certainly makes a huge difference but I don't think it makes much difference in the inside acoustics in general. You still have the same reflective surfaces albeit a more dampened planar surface which is what would make some difference but it would be interesting to measure before and after. I just finished a new room with a vaulted drywalled ceiling. Shingled roof, 2 x 12 rafters filled with R38 fiberglass batts.
I know it's going to be an issue so once we get the area rug in (concrete floor East Texas), the furniture and the system back up, we will deal with it then. Probably panels on the ceiling of some type.