Believe it or not when I took my concealed weapons license class years ago it was in a small room indoors, at the end to ensure everyone has at least had fired a gun before, they handed us an old .22 handgun (maybe a browning? Long time ago) with a silencer on it. And 1 by 1 had us take shots at a small target with a sack of what I assume was dirt/corn/or such behind it.

So around 15 people in a 10 by 30 foot (3.3 by 10 meter) room where we shot at a target with the other 14 people standing behind us. No hearing protection was needed. It obviously is louder than the movies, but amazing to not have our ears ringing in a space so small.

The silencer on such a small handgun is awkward at best. Your natural instinct is to want to hold it up, as it weighs down the front of the gun drastically, but clearly you should/can not fire like that, as the gases will expell throughout the silencer resulting in injury more than likely. That was in Florida, the state which concealed weapons permit is accepted in the most U.S. states during travel. The class, took no more than a couple hours during a single night.