Humph vs. Hmph: What's the Difference?

Humph and Hmph Definitions
Humph
Used to express doubt, displeasure, or contempt.
Humph
(onomatopoeia) A sound, usually made with a closed mouth pouting, indicating annoyance, indignation, disapproval, doubt, or sighing.
Humph
(intransitive) To utter "humph!" in doubt or disapproval.
Humph
An exclamation denoting surprise, or contempt, doubt, etc.