hi, im new to the world of acoustics and have a few questions. my band room/ project studio is a 21x13 basement. i'm putting in ceiling tile(usg r2310)and have bought a few different types of insulation i want to add to the corners and above some of the celing tile. i have a case of 703 2", 43 sq.feet of o.c.R-38 12" fluffy, 48 sq. feet of dow safe touch r19, and 50 sq. feet of o.c.r-19 fluff.

my question is: is it better to fill corners or leave a gap?

Filling the corner is always better, put you can also make 4" panels out of the 703 and straddle the corners. Basically if you have enough to fill all the corners then go that route, but if you only have a limited amount then go with the 4" panels. Covering more of the corner area is ALWAYS better over a thicker smaller area.

what if i stacked 2 bails of r-38(floor to ceiling) and then put the 703 in front of that? are we talking putting the 703 long ways across the corner?

Placing the 2' across the corner. YES filling the corner will work VERY well.

Glenn