This first method is the simplest (not that the other method is hard but it has a tricky part). It will disable the sound for all characters and/or all mounts, but the downside is that you also won't be able to hear the sound of your weapons (like your swords swinging through the air) or the footsteps of your mounts (though this may also be an upside).

To do this, first of all start by closing the game (the patcher can stay open). Then go to your Steam folder. For me this folder is located in C:\Program Files (x86), but for you it could be located in C:\Program Files, or wherever you put it when you installed Steam.
Then go to steamapps -> common -> TERA -> Client -> S1Game -> Config
(C:\Program Files (x86)\Steam\steamapps\common\TERA\Client\S1Game\Config)
In here you must select S1Engine.ini and open it with notepad or whatever text editor you prefer.


Now look for [Engine.Audiodevice] (you can do this using CRTL+F).
Here you will find a list of 'SoundGroups'. The one with "GroupName=Character" is obviously for the sounds of your characters, and the one with "GroupName=Vehicle" is for the sounds of your mounts. To turn off the sound, change the 1 to 0, and save and close the file. That's all!

This method will allow you to disable only the voices of your characters and mounts, and you will still be able to hear the other sounds they make. You can also use it to silence specific mounts or specific characters.

Let's start with the mounts.
First of all start by closing the game (the patcher can stay open). Then go to your Steam folder. For me this folder is located in C:\Program Files (x86), but for you it could be located in C:\Program Files, or wherever you put it when you installed Steam.
Then go to steamapps -> common -> TERA -> Client -> S1Game -> CookedPC -> Sound_Data -> Packages
(C:\Program Files (x86)\Steam\steamapps\common\TERA\Client\S1Game\CookedPC\Sound_Data\Packages)

In this folder you will find the voice files of your mounts. There are about 23 different types of mounts in TERA, and there are 23 Monster_Voice files, so it's safe to assume that each of these files are for mounts (I know for certain that two are). If you don't care for the sounds of any of the mounts, then you can just go ahead and delete all of these, though you better back them up somewhere in case the patcher should need them when a new update comes out. However, if you only want to silence a specific mount, you'll need to know which file is for which mount. I've included a (very very unfinished) list at the end of this guide, if there are any players with more mounts and some time on their hands, please feel free to help out!

For the character voices, continue into the folder called PCVoice. The files starting with PC are the character voices. You can also just delete (and back up) all of these, or you can do it for a specific one if you remember what voice you chose when you created your character. If you have a male character with voice 1, then the file you should delete is PCMale_Voice00.gpk. I have a male character with voice 3 so for me it's PCMale_Voice02.gpk.

The NPC voices, you can find in the NPCSpeechVoice folder (right above the PCVoice folder). Here you can either delete everything, or only the voices that annoy you. I haven't tested out which files are which yet, but you can kind of guess which ones they are by their names. I'll update this guide when I have more time.

Monster_Voice00.gpk - ?
Monster_Voice01.gpk - ?
Monster_Voice02.gpk - ?
Monster_Voice03.gpk - ?
Monster_Voice04.gpk - ?
Monster_Voice05.gpk - ?
Monster_Voice06.gpk - ?
Monster_Voice07.gpk - ?
Monster_Voice08.gpk - ?
Monster_Voice09.gpk - ?
Monster_Voice10.gpk - ?
Monster_Voice11.gpk - ?
Monster_Voice12.gpk - ?
Monster_Voice13.gpk - Horses
Monster_Voice14.gpk - ?
Monster_Voice15.gpk - ?
Monster_Voice16.gpk - ?
Monster_Voice17.gpk - ?
Monster_Voice18.gpk - ?
Monster_Voice19.gpk - Tigers
Monster_Voice20.gpk - Duck and Pig(1)
Monster_Voice21.gpk - Police Car, Raptor, Wolf, Pig(2)
Monster_Voice22.gpk - Dispenser, Sentry Tower
Monster_Voice23.gpk - ?