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In this video I discuss the use of non-diatonic chords in different chord progressions. Non-diatonic chords are not as confusing as their name suggests, and are more common than you might think in chord progressions in various styles of music.
In any major key there are certain chords which are natural to that key. These 'diatonic chords' are based on the triads that have their root on each note of the seven-note major --or diatonic- scale. Chords that aren't based on any of the notes in the scale are called non-diatonic chords.
In this video I use 'Georgia On My Mind' by Hoagy Carmichael to illustrate the use of non-diatonic chords in jazz and blues. This famous song uses two non-diatonic chords in its chord progression.
When it comes to comping or improvising over this chord progression, there's no need to improvise any differently than you would with a completely diatonic progression. This is because the progression is quite jazzy, so improvising over it with the F blues scale or F pentatonic scale creates a distinctive harmonic sound and fits the style well, despite clashing with the left hand.
When improvising or comping in more contemporary music or pop music, we deal with these chords differently than we would with jazz or blues styles.
Many pop and rock songs feature non-diatonic chords, however they usually treat them as a sort of 'mini key-change'. 'Yesterday' by The Beatles is a useful example that I use as a demonstration in this video.
Whether comping or improvising, the melody can't be as independent from the progression as it can with jazz or blues - you can't really mix non-diatonic chords with diatonic melodies. The best way to overcome this is by using scales from the key of the non-diatonic chord when playing the non-diatonic chord.
To be able to do this seamlessly while improvising, practice is essential. Try to find progressions that use non-diatonic chords- most jazz progression include one or two, as well as a lot of Beatles songs. If you like The Rocky Horror Show, virtually every song uses non-diatonic chords.
If harmony confuses you or you'd like to know more about it, check out my book 'How to Really Play the Piano', which has plenty of chord charts as well as a whole section on harmony and blues. I also cover a lot of information on chords, harmony and improvising -- as well as loads of other interesting stuff -- in my earlier videos.