The basic concept that sound waves could be traced or recorded on a solid object was developed separately by Leon Scott, Charles Cros, and Thomas Alva Edison between 1857 and 1877 and, by 1890, the foundation of the present-day commercial record industry was established. Although cylinders were the first sound recordings to be sold commercially, discs were introduced in 1894 and ultimately became more popular. The library collection of sound recordings began with the founding of the Sadie Knowland Coe Music Collection at the Evanston Public Library in 1907 during the acoustic, or pre-electric era (1877-1925) when recordings were still made and reproduced by mechanical means. Following the introduction of electrical recordings, more libraries inaugurated record collections, albeit with some caution, and by the 1940s, the idea that collections of records belonged in libraries had won acceptance. The convenience of the long-playing (LP) record, introduced in 1948, appealed to the public and librarians alike; and stereo, introduced publicly 10 years later, provided the final great improvement for pre-1980s audio recordings. Most recently, direct-to-disc, digital, and compact disc (CD) recordings have resulted in clearer sound reproduction, as well as increased problems of selection, storage, and access for librarians. Ninety-six references are provided. (KM)