"The De-Esser uses a unique technology to reduce sibiliance in a mix or on vocal tracks. It automatically detects and hones in on the sibilant frequencies leaving neighboring frequencies unaffected. These S-sounds are mixed back into the main signal phase-inverted to cancel out the sibilance.
The result is a sound-neutral, inconspicuous and extremely effective process. Even at high S-Reduction values the de-essing has an eligible effect on the character and timbre of the voice."
The Auto Dynamic De-Esser is extremely simple to operate: The S-Reduction control is the only control you need to set. The more it is turned up the more sibiliance is removed.

You can set the detection to better find sibiliance in male or female vocals by selecting the respective Male/Female button.