My new room is 8 x 16 x 32, what to do?

My room in my new house is very close to 8 x 16 x 32. I’m going to have to do something serious to treat it. It is concrete floor, brick walls, and plaster ceiling. It is empty now and it is difficult to talk to someone as it echos for several seconds.

I might build a wall at one end to change the 32 to 26 so the width and length are the golden ratio (16 x 1.62 = 26) but what to do with the height? If use the golden ratio with an 8 foot ceiling I end up 8 x 13 x 21 and I don’t want to lose all that space. I need a 10 foot ceiling for a 16 foot width but I don't think that is going to happen.

If I deaden the rear wall does it really matter how long the room is? Any ideas?