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Well, using voice to replace instruments in music is called a capella. Don't think there's an actual trope for it. Sampling could be when taking different sound samples to make the song.
It's closer to Sampling insofar as, most of the time, the samples are treated as sound effects (of 1/4-2 seconds in length) and relooped as needed; as opposed to toned chant or actual sung words. Somewhat of a Sub-Trope of Sampling -based Remix then. Trying to think of a better name than Poop Remix.
Edited by DonaldthePotholer

Listed under Music as, technically it is music, but it's actually "played" more from places like You Tube.
This is where you have an already existing song, usually from a soundtrack, esp. VideoGames, though it could be any song, replacing the instruments with vocal / sound samples from other works. Common sources for these samples include That Guy With The Glasses, Team Fortress 2, other sources of YouTube Poop, and recently My Little Pony Friendship Is Magic.
Edited by DonaldthePotholer