That's odd...I tested a few ogg-files that were already in SHIII, and they have the same alien-like sound. Can't remember ever having heard that, but I guess it's meant to be that way, and correctly played-back ingame.
To be sure my PC still can play oggs as always, I also tested the ogg-songs I have in my grammophone-folder, and those sound like they have to.
Strange, isn't it?
Anyway, your mod seems to work now...gj, thx!