There are two types of "hmm".
1st type:
What do you want to eat?
hmm.. I'll have the qagh.
2nd type:
So, what's it gonna be? hmm? will you eat the qagh?
I think that we could say with certainty, that both {ghghgh} and {Hu'ma/Hu'mI/Hu} express the 1st type of terran "hmm".
But do they express the 2nd type too?
~ Dana'an
remain klingon