Open up your Left 4 Dead 2 folder located most likely at:

C: Program Files (86x) - Steam - steamapps - common - Left 4 Dead 2 - left4dead2 - sound - player - survivor

In this folder you will find the folder "voice," this contains all the left 4 dead 2 survivor voices, from here you can remove certain audio files, change em, mix and match or silence em all.

Just as a reference though the folder names for the survivors are different from the ones in game so a quick recap:

Gambler = Nick
Mechanic = Ellis
Producer = Rochelle
Coach = well....Coach

Removing these files doesnt hinder your ability to play nor does it pose any problem to running the game it only allows you to play without hearing everyone yelling RELOADING!

For the original survivors just go back to the main Left 4 Dead folder and instead of going into left4dead2 you instead go into left4dead2_dlc2 - sound - player - survivor - voice and there are the original survivors audio files. Same as Left 4 Dead 2 the survivors are named differently

Biker = Francis
Manager = Louis
NamVet = Bill
TeenGirl = Zoey

Hope this guide helps those looking for silent zombie eradication or to just make ellis stop it with his damned keith stories, they were funny the first time now quiet.

Can also help those looking to have an anime character without a dudes voice.