Bach's well-known composition with an extra beat to every bar, then a touch of detuning, delay and reverb added. The source is a 1928 recording by the Rosé Quartet downloaded from the Internet Archive.
More on the 694th weekly Disquiet Junto project, 5/4ify — The Assignment: Add a beat to a pre-existing piece of music — at https://disquiet.com/0694/