deadening vs degradation

deadening and degradation both are nouns.

Word	Noun	Adjective	Verb	Adverb
deadening	Yes	Yes	No	No
degradation	Yes	No	No	No

As nouns, degradation is a hypernym of deadening; that is, degradation is a word with a broader meaning than deadening:

Other hypernyms of deadening include debasement.

deadening (noun)	degradation (noun)
the act of making something futile and useless (as by routine)	changing to a lower state (a less respected state)
	a low or downcast state

deadening (adjective)	degradation (adjective)
so lacking in interest as to cause mental weariness