Briefly reviews the four successive processes used to produce sound recordings: etching sound waves into the surface of tin foil (1877), wax on cardboard, shellac and polyvinyl chloride disks, magnetic tape (cellulose acetate), and the advent of the compact disk. Studies the various playback equipment necessary to reproduce recorded sound, including early devices, cylindrically shaped sound records and circular disks, magnetic tape, and compact disks. The materials used in the manufacture of these groups of objects are all synthetic and slowly degrade with use. The storage conditions contributing to the stability of each group are discussed, and further information is presented on storage of magnetic tape used for recording data. The author indicates that so far little is known about the long-term stability of compact disks. -- AATA