.22 rifle, even indoors, isn't too bad without ear protection. .22 handgun still makes my ears ring, so I wear ear muffs or plugs. By far the worst was the .22 Remington Jet, which was a .357 necked down to .22. No recoil, since the bullets were so light, but the noise and muzzle blast was horrendous. That's what got me kicked off the indoor range at the armory. Far worse than the .45ACP the range was intended for.
The dents the rounds were making in the backstop did not win me any friends, either.
Never had the chance to shoot or hear the .22 Jet; it was a rare breed in the early days and even moreso now. I have heard that the blast was all out of proportion to 'a .22'. That must have been something else, kinda wish I was there. :-)