You'll find them under your install directory and then the Localization folder and various Voice_*.pak folders. You would need to unpack them with Norbyte's tool, but a word of caution: These are all packed as Wwise *.wem files and their names are just some kind of hashed numbers. In order to find whatever snippets you want is going to be a lot of work, and even then may be too impractical to impossible to reuse. I haven't looked to see how the VO is actually mapped to dialogs but Larian have an entire Wwise project file that we don't have access to, which defines the behavior of a lot of the audio.