Hocket

Nick explained this vocal technique to me once when we were talking about Dirty Projectors. It's got a bit of a technical description to go with it, but in the vocal usage it sounds like a call and response where two people alternate the melody line. There's a 14th century medieval tradition that uses this, and I'm reminded of some Meredith Monk recordings...

From Wikipedia:

"In music, hocket is the rhythmic linear technique using the alternation of notes, pitches, or chords. In medieval practice of hocket, a single melody is shared between two (or occasionally more) voices such that alternately one voice sounds while the other rests.

In European music, hocket was used primarily in vocal music of the 13th and early 14th centuries. It was a predominant characteristic of music of the Notre Dame school, during the ars antiqua, in which it was found in sacred vocal music. In the 14th century, the device was most often found in secular vocal music."

What came up on Youtube was this awesome Ethiopian flute video, with twenty four flutes hocketing! They even have a synchronized dance ending.