Two different sounds for different sources, to me. The first, from a person, is sorta like 'huh' but without opening the mouth. The second, as a displaced sound effect, is the scare chord used when you're spotted in Dishonored.
In my opinion "?!" is the emoji for "wtf". You have the question mark for "what". Nobody cares about the "the". The exclamation mark is there for "fuck"s sake.
http://15130-presscdn-0-89.pagely.netdna-cdn.com/wp-content/uploads/2014/02/obama-wtf-485x4071.jpg
I'm done
This is the sound it makes