Way cool, worked on my Dell U3011! How does this function, why does the screen emit a high pitched noise?
White and black pixels take different amounts of power to draw. As the screen scans up and down to draw the various rows, it thus has to rapidly charge and discharge the capacitors. The capacitors are expanding and contracting a bit as they do so, which vibrates the air and makes a tone.
Frankly this sounds like an awesome way to blow up those capacitors.