Glad you clarified the music where "loud" is desireable. I prefer the word "Strong," meself. Shanties and worksongs certainly require a strong voice. That's true of any outdoor singing, where the air swallows your voice. In black gospel, I'd put energy and feeling first, which might translate into "loud" on one song, and soft on the next, depending on the mood of the song. Which makes me think of singers who can rip it up.

Jerry,