If you name a .wav file the same as a POI it will play that one when you approach it.
EG, if you have a POI named gatso.dat and a gatso.wav file, that's the one that gets played.
And once you've got them set up they play when using Centrafuse.
More info here: http://forums.fluxmedia.net/showthread.php?t=1916
Check post #14 for the sound files.