Pocket Harmony provides an interactive map of harmonic relationships in the circle of fifths.
Tapping (marimba) or double-tapping (drone) a key plays the tonic chord of a key, and adjusts the chords at the top of the page to reflect possible harmonies within that key.
The user can select (on the chords page) which harmonies should play at each scale degree. These chords are spelled for the user in the middle staff.
Keys related to the principal key appear in full color, giving the user a sense of -- and an ability to hear -- the harmonic reach and distance of each mode.
We hope you will find it useful on your musical travels.
Please send comments, corrections and bug reports from this page: http://www.timsummers.org/?page_id=18