One sound at a time

The two pictures sit on top of each other, one showing at a time, so any difference shows up as movement. Tap Flip to switch, hold Peek to look at the other one for a moment, or tap Blink. To mark something, tap Mark first: then a tap on the picture pins a comment there and a drag boxes an area. Tap Mark again to scroll. Remove takes a mark away. Then say which picture is the real one, and go on with Next.

The two pictures sit on top of each other, one showing at a time, so any difference shows up as movement. Keys act on the highlighted card: space plays the real sound, F flips, hold Shift to peek at the other, B blinks them. Then answer about the picture showing: M this one is the real one, S this one is ours, 0 can't tell. Enter next card.