Quote:

"smooth out" or normalize...volume irregularities



Normalizing is available, as Rachael says. It does not "smooth" anything, though. It raises and lowers everything by a set amount, leaving the differential as is.

If smoothing is what you actually need, open the thing in the Piano Roll view and go through it lopping off the high velocity spots with the mouse. (Or raise the low ones.) It's remarkably fast.