Turn Audio on and allow the mic. Tap Start — the mic gathers many partials from nearby phones and voices into one chroma picture.
Over time this phone slides its pitch toward the group’s strongest notes (a shared root chord). Hold the circle to sing the aligned tone; release to listen only.
Scale can stay on Auto (major vs minor from the room), or you can lock Major/Minor. Lock root freezes the detected key while you keep listening.
While listening: Tuning is the group key; Offset (¢) is how far this phone’s pitch still sits from that root — it slides toward 0 as consensus locks.
Works best in a circle at moderate volume; avoid covering the mic with your hand.