Upon reading sheet music for black spirituals, I discovered something unusual:
As you might notice, the bass, tenor, alto, and soprano parts are all singing the exact same notes throughout the majority of the melody (with the exception of the chordal ending phrase). Since choral arrangements usually divide vocal parts for harmonies, counterpoint, etc., what is the significance of aligning vocals from different registers?
Is there an implied direction for the unison singing to produce various, contrasting notes, or perhaps, does the effect of unison singing emphasize the one melody (in which case, does it even matter if only person sings it)? I'm looking for a more theoretical/philosophical answer, and would be happy to hear what you guys make of this.