I can't seem to locate the sound files for the normal (non-campaign-specific) units and user interface actions. I found the .mpq files in C:\Program Files (x86)\StarCraft II\Campaigns\Liberty.SC2Campaign, and opened them up with Ladik's MPQ Editor.

The base.SC2Assets file seems to contain some of the sounds, the ones that aren't language-specific. enUS.SC2Assets contains other sound effects, in particular the campaign-specific unit sounds that are dependent on language (as you'd expect from the enUS at the beginning of the filename). For example, I can see all of Zeratul's sounds at enUS.SC2Assets/LocalizedData/Sounds/ProtossVO/CampaignUnits/Zeratul. Where's the equivalent folder for the non-campaign specific units?

Am I just missing something simple here? Where are the generic unit's sound effects?

(x86)\Starcraft II\Mods\Liberty.SC2Mod\base.SC2Assets is where the sounds are