Alternative theories of harmony?

Question

Do you know of any alternative (to functional) descriptive theories of harmony or attempts at creating them? By that I mean attempts to explain both functional and non-functional harmonies in a single and coherent way, focusing for example on voice leading and not function or any other approach. To try to explain better as it indeed might sound confusing: in today's music we come across progressions that are not easy to explain using functional harmony so we invented this term non-functional harmony that seems to be just a way of saying: the established theory doesn't really handle this case very well. Hence the question: is there any research or attempts to create more unified theory of why certain chord progressions sound good and others don't. And I don't really mean microtonal or serial theories but attempts at describing all existing practice of western harmony based on 12-tone scale in a different way.

Answer 1

Check out American composer Harry Partch who created his own musical system and scale . Castor and Pollux is one of his works.

Answer 2

Both Schillinger and Hindemith attempted grand unified theories of this sort.