To reduce echo try to avoid room dimensions that are double (or any multiples) of each other. The best ratios are 1 x 1.61 x 2.61.
Maximize room size, keeping as close to the above ratios as possible (bigger reduces room interactions).
Without a ceiling or walls sound is going to transfer upstairs. (I pulled a drop ceiling out of a finished basement and sound transmission went up greatly.)
Without walls, you'll hear the furnace, air conditioner, gas/propane water heater, softner, etc.
I used lined/insulated flexible ductwork to cut furnace/air conditioning noise.
I also used insulated staggered stud walls and an insulated fiberglass exterior door with weather seal.
I just laid pad/carpet on the concrete.
My only mistakes were using recessed can lights (even though the ceiling space is insulated, it still transmits sound) and not suspending the ceiling to allow it to "float" from the structure above (builder finked out and wouldn't do it).