huh

(with falling pitch) used to express amusement or subtle surprise.

Used to express doubt or confusion.

(with rising pitch) Used to reinforce a question.

(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.

(with rising pitch) Used to indicate that one did not hear what was said.

(with falling pitch) Used to create a tag question.