UTD researcher developing 'invisible' audio speakers



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Posted on March 10, 2010 at 12:11 AM

Updated Wednesday, Mar 10 at 12:11 AM

RICHARDSON — "Tiny" is the new "big" — at least when it comes to the race to invent audio speakers that are invisible to the naked eye.

Scientists at the University of Texas at Dallas are working on ways to cover your walls, TVs and computers with speakers that no one can see.


By turning heat into sound.

Scientifically, it’s an old phenomenon, but Mike Kozlov's new twist is doing it through space-age materials called carbon nanotubes.

What looks like a crude experiment today could have mind-boggling applications tomorrow, like invisible speaker "film" applied to windows or walls.

“Speakers, you know, can be become almost invisible,” Kozlov said.

"They can act as speakers in ways... in places... that normal speakers would have no chance of working,” explained Carter Haines, a UTD undergraduate student who works on the futuristic speakers.

It's all kind of amazing, considering the basic idea is more than 130 years old.

It was dreamed up by a guy who just couldn't quite get the thing right. You may have heard of him before; his name is Alexander Graham Bell, inventor of the telephone.

But not so famously, Bell tried to pass heat through foil to create sound, and it worked… kind of.

“Sound was not loud enough,” Kozlov said.

But now — utilizing tiny carbon nano material — Kozlov is able to make the sound 100 times louder than Bell could.

“They are light, they are transparent. They have no moving parts,” he said.

Here's how they work: The carbon nanotubes convert Haines' piano scale into micro bursts of heat. The heat from the speakers moves the air around. That makes sound, and you can see it all happen using a thermal camera.

"The air is moving, but you're not moving the air by pushing it back-and-forth like you normally would, Haines said. "You're moving the air just by heating it up.”

 Imagine covering windows with see-through speakers to create a literal wall of sound.

Or, using noise-canceling technology, you could create complete silence.  "We can suppress, cancel sound coming from outside,” Kozlov said.

The possibilities — from quiet airplane cabins to blasting smart phones — are limitless.

Kozlov says several companies are very interested in his research. While it may be hard to rival the invention of the telephone, taking an old idea and giving it new life would certainly ring Bell's bell.

E-mail dschechter@wfaa.com