This site talks about pitch, octaves and harmonies. I think this site is a good place for me to study my subject because the author, Jeffrey Rosenthal, is a professor in the Department of Statistics (DoS) at the University of Toronto. In one section of this article, it states that the reason some notes work well and some don’t. ( Example: C and G sounds good while C and E flat don’t sound well) This is because mathematics decide whether they sound good or not. Each note has a different pitch and frequency that determines if they are compatible with other notes. All notes can sound good under context (It all depends on the key of the piece).