A user interface implemented on a touch-sensitive display for a virtual musical instrument comprising a plurality of chord touch regions configured in a predetermined sequence, each chord touch region corresponding to a chord in a musical key and being divided into a plurality of separate touch zones, the plurality of chord touch regions defining a predetermined set of chords, where each of the plurality of separate touch zones in each region is associated with one or more preselected MIDI files stored in a computer-readable medium. In some embodiments, the touch zones are configured to provide different harmonic configurations of a base chord associated with the chord touch region. Some harmonic configurations provide progressively wider harmonic ranges across each adjacent touch zone. Other harmonic configurations can provide chords with a progressively higher relative pitch across each adjacent touch zone.