low pitch vs deepness

low pitch and deepness both are nouns.

Word	Noun	Adjective	Verb	Adverb
low pitch	Yes	No	No	No
deepness	Yes	No	No	No

As nouns, deepness is a hyponym of low pitch; that is, deepness is a word with a more specific, narrower meaning than low pitch:

low pitch (noun)	deepness (noun)
a pitch that is perceived as below other pitches	the quality of being physically deep
	the extent downward or backward or inward
	a low pitch that is loud and voluminous
	the intellectual ability to penetrate deeply into ideas