That should be included with the audio toolbox after R2019a.
The files should be in $MLROOT/toolbox/audio/samples/
where $MLROOT is the installation directory
EDIT: I take that back. That's where I'm led to believe they're supposed to be, but in R2019b, they're .wav instead of .mp3. I don't know if .mp3 versions were included in later versions or something. I imagine you could use the .wav file for the same purposes anyway.