When Harry S. Truman became president on April 12, 1945, he inherited the RCA Continuous-film Recording machine that Roosevelt used during the 1940 Presidential election campaign. There are approximately ten hours of recordings from the Truman administration that were recorded between 1945 and 1947, with the bulk of the recordings dating from 1945. Very few concrete facts are known about these recordings and of the ten hours of recordings, only a few hours consist of intelligible conversation.
The sound files can be downloaded in two formats: FLAC and MP3. Each has benefits for different uses.
MP3: good sound reproduction, smaller files, universally compatible. Very good for telephone or Dictabelt recordings and for general listening. If in doubt, try the MP3 versions first.
FLAC: excellent sound reproduction, larger files, growing compatibility. Recommended for meeting recordings and transcribing where the highest sound quality is required. In terms of sound quality, FLAC files are identical to WAV or AIFF files.
More detailed information is available here.