I'm not sure I agree or that speaking softly is supported by studies.
The thing that is true is that women tend to emphasize through frequency changes
while men use changes in volume to emphasize.
But, from the many conversations I've been privy too, I would not say women speak softer.
As for stacatto, women tend to pause longer between words so in fact, leaving more space
for interuptions, men tend to move from words to words which may leave a sense of
speaking faster when in fact they just are not leaving anybody interupt.
So women in fact speak those words faster, but on the whole, the spead
of men and women is the SAME.