Let's make this clear at the very start: the only “silent” hair clippers you're ever going to find is a pair of scissors. Electric hair clippers are going to make noise; They're powered by a motor, and while engineers can do amazing things to damp the noise a motor creates, they can't completely eliminate it. Clippers do their work when two pieces of metal contact each other at high speed, and if that speed is lowered to a great degree in order to reduce noise, the clippers won't cut hair.