The
BBC Sound Archive contains the archived output from the BBC's radio output. Widespread recordings exist in the archive from the mid-1930s, when recording of programmes and speeches were kept for rebroadcast; the catalyst for this was the launch of the
BBC Empire Service in 1932 and the subsequent rebroadcast of speeches from political leaders at a time convenient in the different time zones. Prior to this, the broadcast of recordings was seen as being false to the listener and was avoided. Any recordings made were frequently disposed of and it was the efforts of
Marie Slocombe, who founded the Sound Archive in 1937 when she retained recordings of prominent figures in the country, that the archive became into being officially when she was appointed the Sounds Recording Librarian in 1941. Today, all of the BBC's radio output is recorded for re-use, with approximately 66% of output being preserved in the Archives; numerous
gramophone records made from both shellac and vinyl, as well as numerous more recordings on
tape, CD and on
digital audio tape (DAT). The difficulty of these different formats is the availability of the machines required to play them; some of the records in the archive are 16 inches in diameter and require large
phonograph units to play, The Radio Digital Archive has been capturing radio programmes as broadcast quality wav files since 2008, with over 1.5 million recordings, a number growing daily. Some of the wax cylinder collection has been donated to the British Library. The Sound Archive is based at the BBC Archive Centre in Perivale, along with the television archive, and was previously based at Windmill Road, Brentford. ==Written Archives==