How does this toy work? Faster you color, the faster the music goes.

Factual Questions
1

This is the toy.

I know it has to be simple, but I am having a totally blank mind on this. Basically, the toy has some slots to put a sheet of paper in. You take crayons(or anything) out and draw on it. The faster you draw, the faster the music goes. As you slow down or speed up, the music quite accurately slows down or speeds up, matching your drawing speed.

It works with a drum stick and no paper, so it is pressure based. My confusion is that I don’t get how it adjusts to the speed so accurately no matter where you are pressing. You can make tiny little circles or big squiggles and the only thing that matters is how fast the object moves across the drawing area.

Here is a decent video of someone using it.

2

Since it’s an electronic toy (instead of a mechanical one), can’t it just be a primitive touchscreen tied to a chip that digitally speeds up and slows down the music?

3

It probably uses a cheap resistive touch sensor. Those can detect absolute position, so it would be easy to determine how fast the stylus is moving.

4

It’s probably very similar to the device in this patent.

5

Anyone have further insights on this toy? It’s quite neat, actually.