Merrill Garbus, singer and mastermind of Tune-Yards, once said that it was hard to comprehend, when listening in a live setting, just how complicated the music that her band plays actually is. Blame that on her voice, which is so elastic -- powered by an unrestrained energy that in a flash is molded into rage, then glee, then nonsense -- that the polyrhythms and broad harmonies that support it can feel like backup.

The effect was evident in Tune-Yards' second show at New York's Webster Hall last night, as Garbus muttered, squawked and sang, each utterance remaining somehow tuneful and sweet.

Nowhere during last night's set was this more evident than during the showstopping encore, when opening band Sylvan Esso's Amelia Meath joined Garbus for a stripped-down version of 'Rocking Chair,' a slight, ragged tune from Tune-Yards' latest album, 'Nikki Nack.' Both singers were a little teary-eyed -- it was Sylvan Esso's last show with Tune-Yards, and the last show of a several-week tour stretch for each band -- and the performance put forward the strange and beautiful voices of both women, backed rhythmically by Garbus jumping on the stage (check out the clip above).

Garbus worked the stage similarly during her band's set, as the rest of the group, arrayed around her in symmetry like wings, pounded away at songs like 'Water Fountain.' The complicated rhythms and harmonies may make Tune-Yards what they are, but it's Garbus' otherworldly voice that forms its core.

Check out some photos from last night's show:

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