Their voices float eerily across more than eight decades, ghostly echoes of a fabled operatic golden age: Nellie Melba, Emma Calvé, Jean de Reszke, Lillian Nordica and others, recorded live at the Metropolitan Opera by an enterprising music lover armed with an Edison cylinder machine. The sound is strictly low-fi, the scratchy surface noise is sometimes overwhelming, and the tantalizing fragments often break off abruptly with a singer in mid-phrase. But listening to them is thrilling, like hearing Lincoln recite the Gettysburg Address.
Between 1900 and 1904, the Met's London-born librarian, Lionel Mapleson, immortalized dozens of performances from his perch in...