The Machine That's Saving the History of Recorded Sound

A device in the basement of the Library of Congress produces images of sound, echoing the reason recording devices were invented in the first place. 
Digital conservation specialist Peter Alyea at the Library of Congress. (Shealah Craighead/Library of Congress)

When recorded sound was in its infancy, more than 150 years ago, inventors still hadn't answered what was, to them, a fundamental question:

What does sound look like?

They knew what sound sounded like, of course, and even what it felt like but what would it mean to see sound on paper? It was this question that inspired the French inventor Édouard-Léon Scott de Martinville to design the phonoautograph, which is widely considered the earliest sound-recording machine. His theory was that if he could build a device that transcribed sound, he could read sound the way we read text.

"No one had really looked at sound waveforms before so he didn't really know," said Peter Alyea, a digital conservation specialist at the Library of Congress. "So he created basically what is, in current and modern terms, an oscilloscope."

Phonoautograph circa 1860. (Wikimedia Commons)

De Martinville's device, modeled after the human ear canal, worked by having a stylus attached to a piece of parchment. "And so he just etched it with a diaphragm that would vibrate a little hog's bristle as he spoke into it," Alyea said. "He wasn't interested in actually recording sound and playing it back, he was interested in recording sound so he could look at it. He thought he could read the waveforms. He thought he could take someone speaking and transcribe something like, 'The cow jumped over the moon.'"

The inventor found, of course, that sound waves couldn't be read like text. The visual representation of sound varies based on amplification, not enunciation. But through his experiment, de Martinville ushered in a new era of recorded sound, the implications of which are too enmeshed in the technological world as we now know it to fully appreciate.

Here's de Martinville's April 9, 1860 recording of the French folksong, "Au Clair de la Lune," the earliest known recording of a human voice:

The clip is an odd and ethereal treasure of de Martinville's legacy. But more than that, it is a reminder of the inherent physicality of recorded sound. It took the engineering of new machinery to capture that wobbly strain at all, and more machinery still to resurrect it 148 years later. 

 "Au Clair de la Lune" is all over the Internet now, having proliferated digitally and endlessly since it was first discovered in 2008. (Before that, researchers believed a recording of Thomas Edison had made the earliest recording in the 1870s.) But in order for de Martinville's lost 20 seconds of melody to be found for the Internet age, scientists first had to figure out a way to turn his fragile paper recording—the transcription of sound de Martinville hoped he would be able to read—back into song that could be heard. 

To do so, researchers at Lawrence Berkeley National Laboratory used a combination of optical imaging and high-resolution scanning, then converted the patterns they captured into readable—that is, playable—sound. The technology, originally developed by particle physicists, allows for optically recovering sound recordings without touching the medium on which the sound is recorded. This technique has been around for more than a decade now. The machine invented at Berkley is now, through a partnership, the center of sound preservation efforts at the Library of Congress. 

"They called it IRENE because the first recording they did an image of was 'Goodnight, Irene,' by the Weavers," Alyea told me. "And then they made it a reverse acronym and decided it would stand for Image, Reconstruct, Erase Noise, Etcetera."

Close-up of vinyl record (flickr/Stewart Black)

IRENE lives in the cool basement of the library's James Madison building. It looks, well, like a machine—all metal and lasers and motor—a little bit like a cross between a microscope and the guts of a home printer. How IRENE works: It's basically a digital-imaging device. So, say you have a vinyl record you want to preserve. IRENE scans the topography of the disc, and sends the images it produces to a computer. Separate software on the computer then converts those images into sound. 

"You have optics that magnify the surface of the disc," Alyea said. "You have a laser  that actually drives a motor that moves the whole system up and down like the autofocus on your camera. Most of these discs are not flat at all and there's a fairly small area of focus. Some light comes in here and is split and shone directly on the surface of the disc, and then there's a camera." More simply, IRENE is a mapping device that tracks the terrain of a recorded medium—like the pattern of the grooves etched onto a flat vinyl record. 

The device knows how to image the architecture of other recorded formats, too, including older shellac-coated vinyl, and glass records like the ones made during the rationing of World War II. In the ten years since IRENE was invented, institutions have discovered a spate of esoteric formats and unknown recordings, strange items in long-forgotten collections that haven't even been catalogued. 

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Adrienne LaFrance is a senior associate editor at The Atlantic, where she oversees the Technology Channel. Previously she worked as an investigative reporter for Honolulu Civil Beat, Nieman Journalism Lab, and WBUR. More

Her writing has appeared in The New York Times, The Washington Post, Gawker, The Awl, and several other publications.

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