HUH

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

Example: "Huh! i'm sure i locked it when i left."

Used to express doubt or confusion.

Example: "Huh? where did they go?"

(with rising pitch) used to reinforce a question.

Example: "Where were you last night? huh?"

(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.

Example: "(agreement) a: "murder is bad." b: "huh!""

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

Example: "Huh? could you speak up?"

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

Example: "It's getting kind of late, huh?"