Peter Jackson, the director of the 2021 documentary series The Beatles: Get Back, developed a machine learning system to separate the sound of The Beatles' voices from the sound of their instruments (a process known as demixing) to clean up 150 hours of rehearsal audio recorded in mono in 1969.
https://www.morson.com/blog/2021/12/machine-learning-artificial-intelligence-films-Beatles
https://collider.com/peter-jackson-the-beatles-get-back-interview-demixing/