Most students of American history will remember that without telecommunications pioneer Alexander Graham Bell, the iPhone would never have been invented. But Bell’s trailblazing work in the field of sound recording is frequently overlooked. In the late 19th century, his D.C.-based Volta Laboratory invented the first method of capturing and playing back sounds. One of the first sounds the researchers recorded was Bell’s own voice, but those recordings were thought to be lost—until recently, when researchers from Smithsonian’s National Museum of American History and the Library of Congress discovered a wax-on-binder-board disc inscribed with Graham’s initials (pictured). Using a special sound recovery process developed at California’s Lawrence Berkeley National Laboratory, the historians made the disc audible to human ears. Now listeners can access those recordings in the museum’s new exhibition, “Hear My Voice.” Attendees can examine documents, recordings, laboratory notes, and equipment from the Volta Laboratory, plus listen to Bell’s until-recently unknown voice with their own ears. Though Bell spends most of his time on the disc reciting numbers and simple phrases, his work marked the first step toward our MP3-ruled world. The exhibition is on view daily 10 a.m. to 5:30 p.m. at the National Museum of American History, 14th Street and Constitution Avenue NW. Free. (202) 633-1000. americanhistory.si.edu.