Typically, the action (slide and bolt) make more noise than the round being fired. It’s kinda like “clack clack clack”.
Repeated exposure to suppressed center fire discharges can cause hearing damage. 30db (or whatever) or reduction still leave lots of sound, in the realm of power tools, and such.
The difference is, .22 (target long rifle rounds) and .45 are BOTH sub sonic. You’d be surprised. Yes, suppressors are just that, used for suppressing (reducing) recoil, muzzle rise, flash, and sound.