8,720
edits
Changes
m
→Augmented 9th
'''---------A9---------'''
Similar to the Dominant Minor 9th, this chord extends the Dominant 7th, but rather than adding the m9, it adds a an A9 (same as a m3 from root). Thus, it contains both the m3 and M3 intervals in relation to the root note. As crazy and dissonant as that might sound, this chord is used fairly regularly, particularly in blues which makes use of the m3 as a blue note without necessarily abandoning use of the M3. It appears not simply in jazz but also in rock, being the main chord of '''Jimi Hendrix's''' ''Purple Haze''. It has an ambiguity to it that allows it to function in a number of roles, but will most commonly be found as the tonic in a blues (or bluesy) progression.
The 5th is optional, which is pragmatic for fingering as seen below. While this drops the a pair of m3 intervals, the A9 interval is an m3 + an octave anyway. Since this chord has the potential for dissonance, dropping the 5th is recommended to make the chord more consonant and less complex.