[In the meantime Evan's struck up a hover as best he can next to the crystals, helped by clinging with his fingertips to a ridge in the hard-edged structures. He's frowning fiercely at the crystals -- or at the creature behind them, it's hard to tell.]

That does sound remarkably like a call-and-response.

[He opens his mouth, thinking to try the same, but reddens a little and snaps it shut again. No, he's not going to make an ass of himself trying to sing.

Instead he cranes to peer at Celena's amber again, noting the swiveling view they're getting.] What's she doing? Jo, I mean?