bass voice vs singing voice

bass voice and singing voice both are nouns.

Word	Noun	Adjective	Verb	Adverb
bass voice	Yes	No	No	No
singing voice	Yes	No	No	No

As nouns, singing voice is a hypernym of bass voice; that is, singing voice is a word with a broader meaning than bass voice:

bass voice (noun)	singing voice (noun)
the lowest adult male singing voice	the musical quality of the voice while singing