this one is a little difficult to decode because it relies on you “reading” music. this ones my favorite from the ones he told me.
the notes of sheet music are A, B, C, D, E, F, and G, it depends on how many notes there are for that audio clip.
for example, if you get... lets just say A, C, C, D, C, A, C, C, D, C, B, as a code, your code will in turn be 2621 because of 2 A notes, 6 C notes, 2 D notes, and 1 B note.