Answer: A Talking Clock

The oldest recording in the world that can still be played natively (on the device it was created for) is The Experimental Talking Clock, created by 19th century inventor Frank Lambert in 1878.

Unlike many early recordings (such as the April 9, 1860 phonautograph recording of Au Clair de la Lune discovered in 2008), which need to be digitally scanned and decoded by a computer for playback (as no original playback devices have survived to the present), Lambert’s recording is permanently built into the device that plays it.

The lead cylinder contains recordings of Lambert speaking the hours of the day as well as various chimes and bells to signal different demarcations of time.