Upvote:3
You might find this site interesting: https://www.firstsounds.org
First Sounds seeks out the world's oldest sound recordings—wherever they are. We rewrote history in 2008 when we discovered and resurrected humanity’s first recordings of its own voice, created in 1860 in Paris by Édouard-Léon Scott de Martinville. Since then, we have identified and played back even older recordings. First Sounds remains the authority on Édouard-Léon Scott de Martinville and his recordings.
In other words, the earliest available recordings for your hearing pleasure are those made by the inventor of the phonautograph, the earliest known sound recording device in the late 1850s.
I'd put forward in passing that you can go earlier in time than that by simply visiting Quebec. Linguists widely believe that they speak French with an accent similar to how it was spoken in the 17th century. Or for that matter, as suggested in the comments, rhymes in poetry give good hints on how people spoke in a given time period.