hearing loss vs tin ear

hearing loss and tin ear both are nouns.

Word	Noun	Adjective	Verb	Adverb
hearing loss	Yes	No	No	No
tin ear	Yes	No	No	No

As nouns, tin ear is a hyponym of hearing loss; that is, tin ear is a word with a more specific, narrower meaning than hearing loss:

Other hyponyms of hearing loss include tone deafness, deaf-muteness, deaf-mutism.

hearing loss (noun)	tin ear (noun)
partial or complete loss of hearing	insensitivity to the appropriateness or subtlety of language
	an inability to distinguish differences in pitch