Thursday, May 13, 2010

The Vocoder: From Speech-Scrambling To Robot Rock

The Vocoder: From Speech-Scrambling To Robot Rock
by NPR Staff

If you've listened to pop music in the past 40 years, you've probably heard more than a few songs with a robotic sound. That's thanks to the vocoder, a device invented by Bell Labs, the research division of AT&T. Though the vocoder has found its way into music, the machine was never intended for that function. Rather, it was developed to decrease the cost of long-distance calls and has taken on numerous other uses since.

Music journalist Dave Tompkins has written a book about the vocoder and its unlikely history. It's called How to Wreck a Nice Beach: The Vocoder From World War II to Hip-Hop.

Tompkins says the machine played a significant role in World War II. After the U.S. government discovered that Winston Churchill's conversations with Franklin D. Roosevelt were being intercepted and deciphered by the Germans, it decided to invest in speech-encoding technology. So the National Defense Research Committee commissioned Bell Labs in 1942 to develop a machine — and Bell Labs delivered.

The vocoder wasn't without its flaws. Intelligibility of speech sometimes proved a problem, but Tompkins says pitch control was a bigger concern.

"They didn't mind world leaders sounding like robots, just as long as they didn't sound like chipmunks," he says. "Eisenhower did not want to sound like a chipmunk."


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