Acoustic Monitor Turns Any Surface into An Input Device

Why spend hundreds of dollars on high tech input devices when you might be able to get the same actions out of scratching your fingernail against a wall? Chris Harrison from Carnegie Mellon University debuted his new form of “scratch input” at SIGGRAPH this summer. Using a rudimentary acoustic sensor attached to any hard surface, Harrison’s scratch input interprets contact with the surface as predetermined commands. Move the sensor to a new surface and you can still use those commands. Harrison has turned any surface into a simple input device. Check out his monotone demonstration video after the break.

The most annoying sound in the world just got useful.
The most annoying sound in the world just got useful.

We first got interested with Chris Harrison because of his deformable touch screen technology. The guy’s just a graduate student and he’s making some pretty amazing gadgets. However, we should point out that when it comes to acoustic sensors and scratch input Harrison’s isn’t the first, or even the most sophisticated. A EU based research project, Tangible Acoustic Interfaces for Computer Human Interaction (TAI-CHI), was able to create a real one-to-one version of scratch input back in 2005-2006. Check out their demo video below; it’s brief but impressive.

Harrison and Scratch Input (2009)

TAI-CHI (2006)

Now, I’m not trying to do some big expose here. It’s very likely Harrison new all about the earlier TAI-CHI work because there are some major differences between the two projects. First, Harrison is looking for just five or six inputs and not much more. TAI-CHI was trying to create a way to record absolute positioning and motion. That’s why Harrison can use a stethoscope and TAI-CHI has to have four piezo-electric transducers working in tandem. You can see this in the examples they provide. TAI-CHI demonstrates how to use a board like a notepad. Harrison is showing cool ways to control a radio or mute a cell phone. The two projects have very similar principles, but produce very different technologies.

That being said, both projects have much the same implications, albeit on different ends of a spectrum of sophistication. These devices will allow users to rethink what constitutes an input device. Back in 2006, TAI-CHI toured with a program that allowed a user to play the piano on any hard surface. Similar applications (including the notepad type software shown in the demo) could be used to replicate a computer mouse, or keyboard. Though TAI-CHI officially ended in December 2006, its collaborators are continuing to publish papers that refine the complex mathematics necessary in their device.

Harrison’s end of things are much more down and dirty. I can see cell phones and laptops coming with simplified scratch input just as the video demonstrates. Emergency shut-off switches could be incorporated into industrial machinery that utilize scratch input of some kind. In fact, I favor Harrison’s kind of acoustic input devices because they are so simple. It seems more likely that third party developers will come up with more innovative uses for a simple device than for a complicated one.

Then again, if scratch input was going to take off, it might have already done so. Almost three years since TAI-CHI finished and I don’t see the technology springing out of stores anywhere. What I do know is that human-computer interfaces are evolving. Whether or not scratch input is part of that evolution, the way we conceive of interacting with our computers is going to change. My grandfather could flip channels on his TV by dropping a fork, maybe I’ll be able to send an email the same way.

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