Perhaps “silence” isn’t the best term because the sound that these bad-boys emit makes the hair on the back of my neck stand up. Say hello to the Boys of Silence! The Boys of Silence are the watchdogs of Columbia in BioShock Infinite; think of them as roaming surveillance cameras. If they detect you, they will send out an ear-piercing shrill that calls in reinforcements to make your life very (VERY) difficult.
You can’t help but wonder what sort of horrible being lives under that massive mask... scary I tell you. Just plain scary.