how do these work

[the_flatlander 10+ year member]

http://cgi.ebay.com/Ultrasonic-DIRECTED-SOUND-SYSTEM-Speaker-laser-Audio_W0QQitemZ5835350984QQcategoryZ3276QQrdZ1QQcmdZViewItem

I don't get how these can send sound to just a certain area? So if you step out of the "beam" by like 3" you wont hear any sound?

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[squeak9798 5,000+ posts]

I don't know if those actually function as advertised.....but I do remember a technology coming out a year or so ago that claimed the same thing. Basically, think of it like a laser.....only instead of a red beam of light, it's emitting sound.