Spawnmobj "deaf" things
Spawnmobj can set the facing angle/height (position) of a thing and the actual def it is attached to can be set to only activate on certain skills or game modes. But there is absolutely no way to spawn a thing deaf currently.
Whilst I'm writing about spawning mobjs via xg during a map. I might as well suggest an additional xg def flag to make things spawned by spawnmobj, that have the countkill or countitem flag's be added to the intermission screen counters rather than making it go over 100% (i.e. like Arch Vile resurrections do). But I'd imagine that one may be quite a long shot.