loudness vs gaudiness

loudness and gaudiness both are nouns.

Word	Noun	Adjective	Verb	Adverb
loudness	Yes	No	No	No
gaudiness	Yes	No	No	No

As nouns, loudness and gaudiness are synonyms defined as:

Other synonyms of loudness include brashness, flashiness, garishness, glitz, meretriciousness, tawdriness.

loudness (noun)	gaudiness (noun)
the magnitude of sound (usually in a specified direction)	strident color or excessive ornamentation
tasteless showiness	tasteless showiness