unmodulated vs monotone

unmodulated is not a noun while monotone is a noun.

Word	Noun	Adjective	Verb	Adverb
unmodulated	No	Yes	No	No
monotone	Yes	Yes	No	No

unmodulated (noun)	monotone (noun)
	an unchanging intonation
	a single tone repeated with different words or different rhythms (especially in rendering liturgical texts)

unmodulated (adjective)	monotone (adjective)
characterized by lack of variation in pitch, tone, or volume	of a sequence or function; consistently increasing and never decreasing or consistently decreasing and never increasing in value
	sounded or spoken in a tone unvarying in pitch