Many old audio documents are so fragile that playing them would destroy them.

In early 2000, south of Oakland, California, a physicist stuck in traffic was listening to the radio. He heard Mickey Hart, a drummer for the Grateful Dead, say that the archives of the world’s aboriginal musics were deteriorating and needed attention. The bulk of the archives had been assembled between 1890 and 1940 by ethnographers using antique devices that recorded mainly on wax cylinders and aluminum disks. Many of the recordings had not been played for a number of years and had grown so fragile that the pressure of a stylus might destroy them.