From Tim: “I’ve been curious to develop my harmonic conceptions and harmonic hearing for a long time… during the course of this curiosity (which continues), I developed some software over the years, the latest piece of which is this colorful little harmony app for the iPhone. I can’t speak, necessarily, to how useful it is. (I can’t speak to how useful an iPhone is, in any broad sense.) But I have enjoyed building it and found that it clarifies my ideas about harmonic relationships.
“I decided to color-code chords within keys to keys in such a way as to make their shared content clearer, if not absolutely clear. And then, of course, the sounds are there to be heard with the colors.” It is available at the iTunes store. http://itunes.com/app/PocketHarmony
Works on iPhone and iPod touch. Comments and suggestions welcome.