videos in AudioSet
A list of about a million ten-second YouTube clips, each labelled with the sounds in it, that Google published in 2017. Labs use it to train and test general audio and music models.
Including Frank Martin: Concerto per clavicembalo e piccola orchestra (1951/1952), Andrew Imbrie: Violin Concerto (1954), Dieter Schnebel: In Motu Proprio (1975)