For several years now, historical preservationists have been stepping up efforts to transfer millions of hours of precious, perishable sound recordings to a single, stable format. At the Library of Congress, technicians are working feverishly to convert their huge collection of tapes, CDs, LPs, eight-track tapes and other audio formats to a playback format that will stand the test of time. NPR's Rick Karr reports on an effort some observers call foolish.