What did Alexander Graham Bell's voice sound like? Scientists help find out
Berkeley Lab's sound-restoration experts have done it again. They've helped to digitally recover a 128-year-old recording of Alexander Graham Bell's voice, enabling people to hear the famed inventor speak for the first time. The recording ends with Bell saying "in witness whereof, hear my voice, Alexander Graham Bell." Berkeley Lab's Carl Haber and Earl Cornell developed the noninvasive optical sound recovery technology that gave Bell's recording a second life. Their method is derived from work on instrumentation for particle physics experiments. It acquires high-resolution digital maps of the surface of audio media without touching them. It then applies image analysis methods to recover the data and reduce the noise of scratches and other damage. A few years ago, Haber and Cornell set up this technology at the Library of Congress, where it's used to digitally restore audio recordings that are too fragile to play. This analysis was conducted at Berkeley Lab earlier this year. The work required help from Engineering Division staff, who developed the gear and belt seen in the image above. This enabled the drum to be rotated at a slow, steady rate so it can be optically scanned.