I spoke to HCS about this already. It's a matter of it being a sound effect.
All of the music in the USF set plays by default. I only found a way to mute channels from the USFLib, so the different song renditions could be played.
Since the ghost voices don't play, and nothing I did to the USFLib changed that fact, and just listening to the voices and wind told me that they weren't synched with the music, I agreed with HCS on the matter that it wouldn't be feasable to include those.