What is music?

It's just a whole bunch of sounds. But why do we like it and get addicted to it? Why music makes us happy and sad? Why do we recognize scales, and make them cyclic?
It seems there is a link between music and the spectrum of light: C,D,E,F,G,A,B ~ red,orange,yellow,green,teal,blue,violet.  Both music and spectrum of light are cyclic over space and time.