r := RandomChoice[{1, 2, 3, 4, 5}]
g[x_] := RandomChoice[{0.1, 0.2, 0.3} -> {x, {x[[1]]}, {x[[1]],  
x[[2]]}}];
accord := Module[{}, r1 = r; {{2 + r1, 6 + r1, 8 + r1}, {1, 5, 9}}];
scale = {1 + r, 4 + r, 6 + r};
s := g[RandomChoice[accord]] + RandomChoice[scale]
A = Table[{s, Random[Integer, 3] + 1}, {40}];
sn[{a_, t_}] := SoundNote[s, t];
song1 = Sound[{"Xylophone", sn /@ A}, 15]
Export["charles_liu.midi", song1, "MIDI"]