audible vs loud

audible is a noun but loud is not a noun.

Word	Noun	Adjective	Verb	Adverb
audible	Yes	Yes	No	No
loud	No	Yes	No	Yes

audible (noun)	loud (noun)
a football play is changed orally after both teams have assumed their positions at the line of scrimmage

audible (adjective)	loud (adjective)
heard or perceptible by the ear	characterized by or producing sound of great volume or intensity
	(used chiefly as a direction or description in music) indicating that said piece or segment should be played loudly
	tastelessly showy

audible (adverb)	loud (adverb)
	with relatively high volume