What's An Altered Dominant Chord?
Altered dominant chords are used to bring tension and an outside flavor to jazz chord progressions. They generally resolved to an inside chord as the I or a substitute as iii or vi.
Altered chords have one or more notes lowered or raised by a half-step, in other words they contain one or more alterations. These alterations can be b9,#9, b5 (#11) and b13 (#5).
They are generally used by jazz musicians, composers and arrangers as substitutions for diatonic chords for adding dissonance and spicing up the harmony.