If you're looking for the original source files, they are held in the "Originals" folder of the Wwise project. You can right-click on a Sound SFX object and select "Open Containing Folder (**.wav)" to bring yourself right to that file in your explorer.
Sound objects can contain behaviors further than just playing back the source file, though. If you're trying to export audio that has been pitched, layered, etc. you could look into the Wwise Recorder.
Hope this helps!