Most live radio broadcasts run on a seven second tape deley. If somebody swears, the board operator can hit the dump button and cut straight from the tolate broadcast to the lie fate. The former host of jake's wake and bake says hitting the dump button is the thing that keeps boardops awake at night.
There's a particular one-kilohertz tone that is universally understood to be covering up inappropriate words on radio and TV. But there are other options, too, like silence -- so why did this particular *bleep* sound become ubiquitous?
Bleep!