* IMPORTANT * If you have iOS 5.0 installed, you can use ModeMap, an updated version of TonalDrone now available in the iTunes store.
TonalDrone is a play-along practise tool for modal improvisation over chords. It gives the user a complete map of four basic scale patterns (Pentatonic, Major, Melodic minor, and Harmonic minor), along with all of their modes. With the selection of each mode, the TonalDrone provides a set of chords (whose harmonic function appears as a color), each of which can serve as a drone for improvisation in the selected mode.
Each mode can play its notes in sequence (with a marimba sound) when it is selected with a double-tap; each chord plays as a drone (with a 'jazz organ' sound) until it is shut off or until another mode or chord is chosen.
Any of the chords and modes can be played in any key. The keyboard can be dragged left and right to be lined up with any scale.
Above all, the user should play along with the machine, using his or her own instrument, to find the modes and chords of the ears and hands. Although it is possible, reasonable, and conveniently portable to play only through the internal speaker of an iPhone, the user may find the sounds most clear when heard through headphones or a larger speaker system.
We hope you will have fun with it. We do.