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Hi, Robot

The history of the vocoder, cryptography’s top-secret funk machine.


Bell Labs' vocoder exhibit at the 1964 World's Fair.  

The vocoder—code name Special Customer, the Green Hornet, Project X-61753, X-Ray, and SIGSALY—started distorting human speech in earnest during World War II, in response to the excellence of German wiretapping. It worked by dividing a voice into its constituent frequencies and spreading it over ten channels, so that anyone who caught the message in transit would hear only noise. (German spies probably heard something like the droning of bees.) The cost of this security, however, was almost total destruction of the message itself: The voice, reassembled at the other end, came out sounding like a drunk robot. As Dave Tompkins puts it in his mind-altering new history of the technology—a book that has become a kind of underground legend in the ten years since he started working on it—the vocoder produced “an electronic impression of human speech: a machine’s idea of the voice as imagined by phonetic engineers.” Its early adopters were often driven to confusion, frustration, and existential dread. Still, the machine wound up robo-filtering some of the twentieth century’s most crucial conversations: FDR, Churchill, Truman, and JFK spoke through it to navigate D-day, the bombing of Hiroshima, and the Cuban Missile Crisis. Churchill, in particular, was a vocoder junkie. JFK, on the other hand, couldn’t figure out how to work its buttons. LBJ hated it so much he once threw his headset across Air Force One. The title of Tompkins’s book, How to Wreck a Nice Beach, is what the vocoder sounds like when it tries to say the phrase “how to recognize speech.”

The early vocoder was, on top of all this, fabulously impractical. Like most forties electronics, it suffered from pre-microchip elephantitis. The full military version weighed 55 tons and had a footprint, Tompkins writes, of “a three-bedroom home and a garage.” Its air conditioner stood nine feet tall and weighed 10,000 pounds. Moving it required a barge and an aircraft carrier. And yet it was also extremely delicate—a Rube Goldberg machine of nested analog technologies. Each vocoder unit contained, for instance, two turntables that would play vinyl records of random noise (produced by the Muzak Corporation) whenever someone spoke. For a conversation to work, those turntables had to be synchronized with another pair of turntables at the receiving end; if either of them was even slightly off, everything dissolved into gibberish. This meant that every vocoder required, in addition to those turntables, a superaccurate crystal clock with which to synchronize them. The crystal clock required, in turn, a special oven with which to stabilize its crystals. And so on.

As America’s wars grew increasingly abstract—from World to Cold to Drugs—the vocoder shrank and became easier to manage. It went digital. It traded vinyl records for computer punch cards. Eventually it enlisted itself in all kinds of utopian civilian projects: voices for the speechless, a car that allowed paraplegics to drive with their larynx, the educational toy Speak & Spell. In the late seventies, the vocoder began to be marketed to the entertainment industry, promising the magical commodity of “instant robotness.” It made memorable aural cameos in Tron, Battlestar Galactica, and Transformers cartoons.

The vocoder’s most revolutionary effect, however, may have been in the world of pop music—particularly hip-hop and funk, whose pioneers (Afrika Bambaataa, the Jonzun Crew, Grandmaster Flash) managed to turn the machine’s inhuman croak into an instrument of weird paradoxical expressiveness. “The vocoder can be soft and sexy or powerful and demanding,” said a member of the band Midnight Star, whose 1983 hit “Freak-A-Zoid” came at the peak of what Tompkins calls “the vocoder space-helmet party of the eighties.” There were, of course, socioeconomic implications to all of these oppressed voices translating themselves into robo-speak. The vocoder, as Tompkins puts it, represented “the black voice removed from itself, dispossessed by Reaganomics, recession, and urban renewal, and escaping to outer space where there was more room to do the Webbo, where the weight was taken but the odds of being heard were no less favorable.” Today, the past’s voice of the future produces instant nostalgia: Every vocoder anthem I managed to track down on YouTube sounded like it should be playing behind a chase scene in Beverly Hills Cop.

Among the book’s many revelations is that the vocoder’s two cultures—the military and the funky—completely failed to speak to each other. “Of all the World War II cryptology experts I interviewed,” Tompkins writes, “none was aware of the vocoder’s activities in the clubs, rinks, and parks of New York City … Of all the hip-hop civilians I interviewed, none was aware of the vocoder’s service in any war.” It’s a nice irony, given the vocoder’s original function to connect people.

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