"Quite a lot of pop music now tries to marry Western harmony with local melodies from the Middle East, India, and other parts of the world. That can be more or less successful, but one problem is that ...

Notes with frequencies that are in simple whole-number ratios, like 1:2, 2:3 or 4:5, sound good when played together. This is the basis of musical harmony. After unison (1:1) and the octave (2:1), the ...