If you find this interesting, you might want to check out the Topic 7 lecture notes from Bryan Pardo's Machine Perception of Music and Audio course at Northwest

If you find this interesting, you might want to check out the Topic 7 lecture notes from Bryan Pardo's Machine Perception of Music and Audio course at Northwestern University: http://music.cs.northwestern.edu/courses/eecs352/lectures.php http://music.cs.northwestern.edu/courses/eecs352/lectures.ph... Those notes show an example of a spiral pitch representation and discuss chromagrams (mapping complex wave forms to pitch classes) as well as other concepts. For a deeper look, check out the book Signals Sound and Sensation by William M. Hartmann.