I do exactly that fairly regularly and its not such a big deal.
The indoor range that I go to has people shooting .44 Magnums, AR15's (.223 frangible) and shotguns so I am not the loudest by quite a margin.
Shooting indoors with a guy and his .44 Mag on one side and a guy with an AR15 on the other, certainly helps you get over any flinch reflex you may have
It does make you realise that the first thing to go in any real HD scenario would be your hearing.
The one thing you do have to be careful with is hot brass getting wedged between clothing and skin. I have 2 nice scars on my neck from two separate incidents where one of my brass casing bounced off the ceiling and straight down the back of my neck where it wedged against my collar.
A floppy hat solved the problem.