We talked to Robert Putnam, spokesman for the American Technology Corporation, the company that makes the LRAD—the Long Range Acoustic Device, a gadget designed to deliver a very loud and unmistakable, audible sound in a specific direction, creating a 30 to 60 degree beam of sound (rather than all around) to get to the bottom of Lost's sonic fence tech.
It's clear that upon coming up to the fence, this so-called "sonic fence" emits sound inaudible to the human ear. Therefore, the fence must be using some sort of super-low frequency sound in the infrasonic range, which is from 20 Hz down to 0.001 Hz. At these levels, you can't hear the sound, but can still feel it. Exposure to these low-level frequencies can cause a variety of symptoms in humans, from anxiety and extreme sadness to feelings of pressure on the chest and chills down the spine. (Want to learn more? Read about the Infrasonic Concert Experiment in London, where scientists tested the affects of super-low frequencies on humans.)
Can these ultra-low frequencies stun someone? It's not impossible. But could they be used in a fence like the one on Lost? Well, that's less likely.
In order for the fence to function like it does in the show—only affecting people who cross a specific line—the beams would have to be focused in highly specific directions. "That's the problem with infrasound. You can't direct it," Putnam says. "There's really no way to focus it in a certain direction." Therefore, anyone in the area would be vulnerable to the frequencies, including the Dharma Initiative's Amy, who manages to cross the fence with the aid of earplugs—but only after she pulls them from the box that deactivates the fence. The problem is that the lower the sound, the longer the wavelength, so the harder it is to control and direct. Devices like the LRAD use higher frequency sounds that are audible to the human ear. Though ATC has developed the technology to direct their intensity in a certain direction, causing the unpleasant loudness to affect only those in the targeted area.
Sure, there's the chance that Dhamra has developed some high-tech way to concentrate these sounds, but given the electronics and technology available in the 1970s, it's pretty unlikely. And, Putnam says, "to just to be able to put in foam earplugs, then walk across [the line]— that's nothing we're familiar with." —Erin Scottberg http://www.popularmechanics.com/blogs/science_news/4307355.html