1.interjection(with falling pitch) used to express amusement or subtle surprise.
"Huh! I'm sure I locked it when I left."
2.interjectionUsed to express doubt or confusion.
"Huh? Where did they go?"
3.interjection(with rising pitch) Used to reinforce a question.
"Where were you last night? Huh?"
4.interjection(with falling pitch) Used either to belittle the issuer of a statement/question, or sarcastically to indicate utter agreement, and that the statement being responded to is an extreme understatement. The intonation is changed to distinguish between the two meanings - implied dullness for belittlement, and feigned surprise for utter agreement.
"(agreement) A: "Murder is bad." B: "Huh!""
5.interjection(with rising pitch) Used to indicate that one did not hear what was said.
"Huh? Could you speak up?"
6.interjection(with falling pitch) Used to create a tag question.