How the heck does it do that? Japanese telecom giant NTT DoCoMo has used the Mobile World Congress in Barcelona to demo a very cool new handsfree interface you can use to control an MP3 player using gestures you make with your eyeballs. Sensors in the earbuds themselves measure changes in electrical potential to convert your eye movements to iPod commands. Fascinating stuff... and while using it on an MP3 player might seem a bit naff, there's probably a range of other situations where handsfree, voice-free control options like this could be really useful.

So the idea is that the human eyeball has a measurable positive charge at the retina, and a negative at the cornea. Tiny electrodes (electroculograms) on these eye-controlled earbuds are able to detect tiny changes in electrical potential as the eyes move around, and effectively produce a readout of what the eyes are doing in real time.

These eye movements are converted into MP3 player controls - you look full left then right to play/pause the tracks, right-right to skip forward, left-left to skip backward, or rotate your eyes clockwise or anticlockwise to raise or lower the volume.

The Macworld video below seems to demonstrate the device taking a good clean reading as a DoCoMo rep takes the device through its paces - although it's a promo video, not any sort of test. You'd have to wonder how ambient electrical field fluctuations might affect it.

Still, it's a fascinating device and another new form of interface - this time, one that lets you control a device handsfree and voicefree. Eye movements can easily be performed in most circumstances - walking, using a PC, lying down, even driving, cycling or riding a motorcycle, provided it reads fairly quickly.

And while integrating this interface into an MP3 player or smartphone could be a clever way of pushing it into the consumer market, we can't help but think it's destined for some more interesting and less trivial applications down the track. Either way, who would have thought earbuds could measure the position of your eyes? Very nifty.

NTT DoCoMo via Wired Gadget Lab.