Now here’s another gesture interface prototype we’re itching to try. Chris Harrison mounts a simple microphone on any surface — wall, desk, pants pocket, then scratches letters or patterns on that surface to control a computer or mp3 player. Sound carries so well in solids that the audio pattern can be picked up far from the mic, and a two-stroke pattern like the letter ‘V’ is easily distinguishable from a circular one like the letter ‘O’. Chris has in mind using your cell phone’s microphone as the pickup, so any horizontal surface becomes a gesture input device once you put your phone down on it.
Gesture interfaces seem to be falling into 2 categories: 2D, requiring contact like this prototype or a touch-sensitive panel (like Microsoft’s Surface), and 3D, like the camera-based systems we’ve also featured. Their main advantages over last-generation touchscreens is that they don’t need to have a specific target area — you can perform the gesture anywhere in their range — and they can detect complex movements and multiple touches at once, like a chorded keyboard, increasing the encoding capability. These two improvements work better for blind and low vision users, but gesture complexity may foil some users with impaired dexterity.