Depends on what’s being suppressed. Muzzle blast can be mitigated to negligible. Velocity, for some, can be viable subsonic - eliminating sonic crack. A suppressed AR15 is still loud as a full-speed .22LR thanks to viable velocity. A suppressed subsonic .22LR bolt is barely a pfft.
Shot a suppressed standard .45 ACP Uzi a few rounds. Loudest thing was the slapping of the bolt.