Suppressors (the correct term) don't make a firearm totally silent, especially with rifle calibers. The bullets are supersonic, so you still hear a "crack" as the round travels downrange. Depending on the quality of the suppressor, felt recoil, muzzle blast, and muzzle flash are greatly reduced or eliminated.
If you're truly interested in procuring a rifle suppressor, I suggest going with one of AWC's suppressors. I have a Thundertrap for my .308 bolt-action rifle. I can shoot mine all day comfortably without hearing protection.