muffle vs dampen

muffle is a noun but dampen is not a noun.

Word	Noun	Adjective	Verb	Adverb
muffle	Yes	No	Yes	No
dampen	No	No	Yes	No

As verbs, muffle and dampen are synonyms defined as:

Other synonyms of muffle include damp, dull, mute, tone down.

muffle (noun)	dampen (noun)
a kiln with an inner chamber for firing things at a low temperature

muffle (verb)	dampen (verb)
suppress in order to conceal or hide	lessen in force or effect
deaden (a sound or noise), especially by wrapping	make moist
	check; keep in check (a fire)
	make vague or obscure or make (an image) less visible
	reduce the amplitude (of oscillations or waves)
	suppress or constrain so as to lessen in intensity
	deaden (a sound or noise), especially by wrapping