There are versions of the breakfall/highfall which does not require any slapping but are very soft. These soft breakfalls sometimes look as though the person is reaching "behind" them as they fall with their leading hand (which would have been used to slap in a traditional breakfall) to "cushion" their fall.
I do this type of fall sometimes. In my experience it is a result of not knowing when the ground is coming. In other words, most of the time I know where the ground is due to a good solid connection between uke and tori all the way through to completion. It's the really slick techniques, when I can't feel anything from tori, that prompt me to feel for the ground. Those are my favorite by the way.
Sometime I make lots of noise, sometimes I don't...but I always get up.
Also I have to say that I agree with Greg....There is ALOT more to ukemi than just falling....but it is fun.