Mount Wittenberg Orca is a seven-track album born from a 2010 charity concert that raised funds for protected marina areas. The collaboration makes a certain amount of sense, since both Dirty Projectors and Björk have built their sounds on innovative song arrangements and pushing the boundaries of using vocals as an instrument. The ladies from Dirty Projectors christen the opening “Ocean,” approximating the mysterious underworld sounds of whalecalls over analog drones, before Björk takes the lead on “On and Ever Onward,” where Amber Coffman, Angel Deradoorian, and Haley Dekle’s backing vocals sound bred to accompany Ms. Guðmundsdóttir’s inimitable inflections. “When the World Comes to an End” is built in Dirty Projectors’ trademark stop-animation style of production, accented by guitarist Dave Longstreth’s off-kilter, romantic croons.