Sonar fence
From Lostpedia
The high-frequency sonar fence is a continuous stream of high-intensity sound waves generated by a series of evenly-spaced pylons surrounding the Barracks. The range of the waves reaches only as high as the top of the pylons. ("Par Avion") Tending to be lethal, the waves can cause severe cerebral hemorrhaging to humans who pass through them. Although humans can physically breach the barrier before the sonic waves trigger death, the Monster cannot pass between the pylons will the sonar is active. ("Left Behind")
The sonar fence is first mentioned in a DHARMA Initiative orientation film seen by Ben Linus as he arrived on the Island. The film described the fence as serving to protect the Barracks area from the Island's abundant wildlife. Ben encountered the sonic barrier as a child, while running out of his home. He later obtained the code to deactivate the sonic barrier and, as a test, sent a rabbit through the barrier before crossing it himself. ("The Man Behind the Curtain")
Kate, Locke, Sayid and Rousseau encountered the sonar fence on their mission to rescue Jack. According to Mikhail Bakunin, their prisoner, and the DHARMA cabling map discovered by Sayid in the Flame, the fence extends all the way around the area containing the Barracks. ("Par Avion")
Locke appeared to kill Mikhail by shoving him through the barrier. ("Par Avion"). After passing through it, he began shaking violently, foaming at the mouth, and bleeding from the ears. He collapsed on the ground and appeared to die. But Mikhail didn't die; he later helped save the parachutist. ("D.O.C.") After he returned to the Others' camp, Ben comments "I thought you were dead." Mikhail responds, "I am fortunate the pylons were not set to a lethal level." ("The Man Behind the Curtain")
After seeing what happened to Mikhail, Locke, Kate, Sayid and Rousseau made a ramp out of a tree trunk in order to scale the barrier and bypass it. In doing so, they did not break the connection between each barrier pylon, which Sayid guessed was the trigger for the sonic waves. ("Par Avion")
The barrier can be deactivated. Kate and Juliet encountered the inactive fence while running from the Monster. Juliet and Kate cross to the other side, then Juliet enters the code 1623 into a data pad, lifts a panel, turns a knob, and the fence is reactivated. The Monster rushes to Juliet and Kate, but the fence repels it. The Monster cannot break through, and goes away; not however before producing a loud, unusual screeching sound. Juliet explains, "we don't know what it is but we know it doesn't like our fences." ("Left Behind")
Ben used the code 54439 to open the fence controls. This code was changed every day according to the orientation film he and Roger watched upon arrival to the island. The fence intensity seems to be controllable at a continuous scale going from red to green to black, where green is presumably a repelling but less harmful effect. ("The Man Behind the Curtain")
Alex is forced to disengage the fence by Keamy and uses the code '1623' which warns Locke and Ben, by form of the Early warning system. ("The Shape of Things to Come")
Trivia
- A notation near the top of the blast door map states "DHARMA Protocol- No stations past security barrier".
- In Season 1, a fence can be seen in the distance. It is likely a real fence in Hawaii that was accidentally filmed. ("The Moth")
- There are keypads or control panels on both sides of the fence. ("The Man Behind the Curtain")
- A deleted scene from "The Economist" involved Miles passing through the seemingly activated fence without any side effects.
Unanswered questions
| Unanswered questions |
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- For fan theories about these unanswered questions, see: Sonar fence/Theories
- Was the code change automated or manual?
- Why can't the Monster go through the fence?
- If the Monster can fly up into the trees, why can't it fly over the fence?
