Does anyone know how to change the sounds in descr_sounds_units_anims.txt?

I checked over at twc and the wiki and there are no tutorials on this.

I've figured out other sound changes, but whenever I put something new into units_anims, the game won't recognize the changes and uses the old set. Can I add in new 'event ANIM_...' to it?
Where do these get referenced from?

Any help or guidance in the right direction would be appreciated.