Also I believe there is a way to have a certain race have a certain sound. But it would take a god aweful ammount of time and I dont want to press it on you, what you do is you go into the UI, set the default sounds to none, and say you chose undead for your default, we would have a trigger such as
Should your race be undead and they finish building they will play the sound UndeadBuildingComplete. And then we would proceed to do that with all the races. And should the player be any race and choose naga, it would disable the other races sounds and play naga ones. Im not sure if it can be done but its a recommendation.