Digital Home Thoughts: Klang Ultrasonic Speakers

"How can you listen to music as loud as you want without headphones and without annoying people around you? Consider Klang's ultrasonic speakers, which use a 30,000hz frequency to beam an audible wave to a single point."

I like them just because they look like a prop from the original Star Trek and even sound like they were named after a Klingon. The idea is that these are speakers that you can only here when correctly positioned between them. Not sure if this would be practical or necessary at home (why not just use headphones). But they could be kind of freaky in public. I'd love to see them used in cars so people can crank it without disturbing the vehicles around them or the neighborhoods they drive through.