I have not done so myself. But at the indoor range there are two doors. One door goes into the "prep" room where the range master checks your gun and rounds to make sure they are approved and where you put your eyes and ears on. The other door goes to the range itself.
Some genius opened the door to the range while my ammo was being shown and I did not have my muffs on. BANG! BANG! Loud as hell and echoed something fierce. My ears hurt the whole time I was there.
I always wear ear protection.
Brain (Use this one the most)