My son?! Oh, God! I belive you!

          sketch4.midi           sketch4.pdf           sketch4-sheet.pdf
              Refer files;    sketch4.ly     sketch4-sheet.latex     run--multiple.cmd      run--multiple.sh
              Actual files Download; sketch4.tar.gz ( About; 35,300bytes )
       Windows (cmd)>run--multiple sketch4[Enter]      Linux (bash)$ ./run--multiple.sh sketch4[Enter]

This sounds "sketch4.mp3".