There has been a lot of talk over the past few years about the need to preserve early film and video tape. What's been lost in all that noise is the need to preserve the audio as well as the visual.
Being the huge fan that I am of vintage radio drama and comedy, I am very grateful people have, over the decades, saved audio versions of radio programs so that I can listen to them today (which I do, every day). But, like early film, many of the early radio programs have been permanently lost -- either through neglect or just the passage of time.
Many early radio programs were preserved on shellac disks that were something like vinyl records. These have held up well over time, except when they were dropped to the floor (they are very brittle). Other shows have been saved on magnetic tape (reel-to-reel machines) but these have problems with sound bleeding from one part of the tape to the other where the pieces of tape touch. Many shows have been converted to more modern formats: first to vinyl records, then to digital copies.
But it appears even these modern advances may not be enough.
You can read more about the precarious state of affairs of audio history here.
(Thanks to Matt for alerting me to this story.)