Isn't LoL like all online? Are you skyping as you play? Could be a lag thing.
And as for sounds in mods, validate the installation through steam and reinstall the mod. Mods can screw up all kinds of things. I had to update some mods on New Vegas and it made all sound from the Dead Money DLC so quiet, which wouldn't be a problem except for the collars beeping. Couldn't figure out what it was by process of elimination, so I just had to totally reinstall the game and redo all my mods in order to get the sounds back.