“As for Burtner’s music, if you think of what the term “eco-music” might sound like, this was it. There were amplified bowls of water — a la John Cage or Tan Dun — dripping and roiling under musicians’ hands; dried stalks of plants brushing and rattling at each other in hoarse whispery tones; birds’ feathers burr-burring when held against a fan; all interspersed with sharp thwacks of percussion and gently caressing flute lines and Edwards-Burrs’s lulling, semi-improvised singsong that, at some junctures, worked in words culled from audience comments on the app.