Computer-controlled 'singing motor' - 2nd Video

You understood correctly.
I'm glad you like it! =)
Haha, I do this kind of strange thing from time to time when I'm bored. xD

It's a mod of my Bleeper Music Maker program, which you can find on my blog (check my profile for the link). You can use it to make sound out of the internal system speaker and out of your 'normal' soundcard speakers with just the program, but it was kind of a custom setup we used for controlling the motor speed. In other words, motors turn at different speeds, so it will sound out-of-tune with different motors. The hardware is an SSC-32 microcontroller and a SyRen10 motor speed controller.