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 Handel-Halvorsen Passacaglia for Violin and Viola (members of the Kontras Quartet), Alexander Borodin - String Quartet No. 2 in D Major - III. Notturno: Andante (Kontras Quartet)