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 La Traviata: Sempre libera with german hornsound, Humperdinck: "Hänsel und Gretel" - Abendsegen, "Stars of Tomorrow": Trailer "german hornsound"