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Directed Sound

Posted by CmdrTaco on from the stay-out-of-my-sweet-spot dept.

yawningyellowyak writes "Technology Review has an interesting article on directed sound. Ultrasonic 'sound' is sent out from a 'speaker' and the distortion encountered on hitting the air produces hearable sound, but only in certain spots. You could be standing right next to someone and they would hear nothing. One step closer to the cone of silence!"

1 of 251 comments (clear)

  1. A sea of calm by the_twisted_pair · · Score: 4, Insightful

    It would be simple to defeat though. The effect relies on heterodyning a signal (mixing HF to produce an intermodulation effect) so broadcasting white noise above the range of hearing should drown the wanted signal nicely - just like interference on an AM radio. Say a small device located near the billboard - or two piezo drivers on the outside of headphones, heck you could build it into your cellphone hands-free kit.

    Done well, you wouldn't hear a thing; even partial cancellation should reduce the adspeak into something akin to a distant ocean sound.

    I think there would be privacy isues to overcome on the part of the Admen first however - remember the hoo-haa over subliminal advertising?