"About 10 years ago, I happened to hear a report on NPR about the Library of Congress and their large collections of historic sound recordings, which described them in some cases as being delicate, damaged, deteriorating and so forth."
What he did then was apply some of the same optical equipment his lab uses to obtain images of subatomic particle tracks to extract "high-quality sound from degrading or even broken analog recordings" without actually touching those recordings. That allows the sound to be saved without causing further damage to the original recordings.
The MacArthur Foundation explains the process this way:
"A disc or cylinder is placed in a precision optical metrology system, where a camera following the path of the grooves on the object takes thousands of images that are then cleaned to compensate for physical damage; the resulting data are mathematically interpolated to determine how a stylus would course through the undulations, and the stylus motion is converted into a standard digital sound file."
Among the audio that's been preserved thanks to Haber's technique: a recording of Alexander Graham Bell's voice.