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Sound Tripwire

July 18, 2007

A new kind of tripwire uses sound instead of string or laser beams.


A tripwire of sound. I’m Bob Hirshon and this is Science Update.

[Mission: Impossible Theme Music]

At the climax of Mission: Impossible, a labyrinth of laser tripwires protects sensitive government documents. And in the real world, our actual government would like to set up tripwire systems underwater to protect ports and ships. But acoustician Karim Sabra says laser light doesn’t travel far in water.

KARIM SABRA (Scripps Institution of Oceanography):
So if you want to scan the harbor on long distances, the only tool you have is to broadcast sound.

In a proof-of-concept demonstration, his team at the Scripps Institution of Oceanography sent a beam of sound across a harbor to a receiver. If something moving through the harbor cut off the beam, the receiver set off an alarm. Sabra says the next step is training the system to catch only actual threats, and ignore driftwood and large fish. I’m Bob Hirshon, for AAAS, the science society.