Board Thread:News and Announcements/@comment-25396609-20151023163349/@comment-3257939-20151023171418

Considering Neo's voice is confirmed but still a mystery and her Semblance has something to do with illusions, then, that's quite a pretty good guess.

And if you watch it closely, you can notice that she's looking down at something. If it was Jaune, I would pic the sceneario like this: Jaune's lying on the ground and suddenly someone appears he looks up and sees the girl. Then the camera zooms to her face and we hear Jaune say and "Sis!? What are you doing here?"