Innovators at work and in the classroom
Sound Science
An experimental physicist gives history back its voice.
By Sarah Khan
On the Smithsonian Institution’s website is an audio track of Alexander Graham Bell, one of the first people to record sound, saying his own name and trilling loudly.
Bell recorded his voice over a century ago on a wax and cardboard disc. Audio preservationists feared it had become unplayable because of its condition and age. But physicist Carl Haber brought Bell’s voice to the present day. A lead scientist at Lawrence Berkeley National Laboratory in California, Haber has been working for the past 10 years to prevent some of the world’s oldest recordings from being lost forever. He recently won a MacArthur Foundation fellowship, joining 23 others, including jazz pianists, writers, economists, and mathematicians, who will each receive $625,000 over five years to advance societal, cultural, or human rights causes.
Haber joined the lab in 1986, a year after completing a Ph.D. in physics at Columbia University. He mainly develops instruments for detecting the shapes and positions of subatomic particles that are shot out from collisions inside high-energy particle accelerators, such as the Large Hadron Collider at CERN in Switzerland. Those devices include a high-resolution camera that Haber has adapted for audio restoration projects. The camera takes thousands of detailed photos of a fragile record whose grooves can no longer withstand the pressure of a stylus from a playback machine. The photos are then stitched together and fed to computer software that simulates a turntable’s needle following the recording’s bumps and grooves. The result is an audio file – a digital backup – of voices from cultures and societies past.
Haber uses a similar method for three-dimensional objects, like cylindrical wax recordings that he says were popular with early experimentalists like Bell. Versatility is important, Haber said, since early recordings were hardly ever made on traditional vinyl. Bell’s recordings were done on many different media, including metal, wax, glass, paper, plaster, foil, and cardboard, according to the Smithsonian Institution.
“As long as we can image the object, we have a lot of flexibility with what media we can work with,” Haber says. “We’re basically just taking a picture of the recordings, and the differences come out in the way the software handles it.” The approach is named IRENE, for “Image, Reconstruct, Erase Noise, Etc.”
Each project poses engineering challenges to Haber’s team, which at times has enlisted help from Berkeley engineering undergraduates. For instance, lasers must precisely control the movements of the camera and the analog recording in order to keep the camera’s depth of field – on the order of microns – constant. Additionally, the computer software needs to know how to detect and eliminate bumps, cracks, and other discontinuations that would affect playback. Haber hopes some of the MacArthur money will allow his team to refine techniques for preserving severely damaged or broken media.
Haber’s efforts have brought hundreds of century-old collections from the Smithsonian Institution and the Library of Congress back to life. His team also works with smaller institutes, such as the Northeast Document Conservation Center in Massachusetts, where a 3-D imaging system is being built to digitize more than 1,000 samples of New England folk songs and lore recorded in the 1930s and ’40s. In 2008, Haber and colleague Earl Cornell revived the oldest known voice recording, a 10-second paper phonautogram, made in 1860, of the folk song “Au Clair de la Lune.”
Haber’s team has recently begun work on 1930s aluminum disc recordings by Harvard classicist Milman Parry of Slavic oral stories and poems. Important in illustrating the structure of such poetry and relationships between individual poems, the discs are difficult to play manually without damage and need digital sound restoration to preserve the audio.
Haber said that physics research often affects other fields, including medicine, industry, and computing. Spinoffs such as audio restoration are considered worthwhile by the Lawrence Berkeley lab, which operates within the Department of Energy’s Office of Science, because of their overall benefit to society. His project, however, has been largely supported by funders outside DOE.
Until now, preservation science has mainly been the domain of chemists, who lend their expertise to stabilizing antiquities, Haber says. “With sound restoration, there are more places where physicists, electrical engineers, and computer scientists can participate.”
Sarah Khan is assistant editor of Prism.
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