Not only is the choice of chords important, but melodic notes are too; and not even just melodic notes, but interesting ones. In this post, I'd like to highlight a few interesting notes (in terms of note value) and provide some kind of foundation for you upon which to discover and develop your improvisational abilities.
An interesting note is not simply a note which works well against a chord at all times, like a root, a fifth, a dominant 7th... it is a note which sounds particularly interesting because it is either an extension (9, 11, 13) or some flat / sharp version of these, or perhaps a flattened 5th, minor against major 3rd, etc. These notes could be considered a little more 'risky' than the basic 1, 3, 5, 7 melodic choices because, whilst the latter can be played pretty much at all times, the others cannot, so it is important to know when to use them... and then how, without causing peoples' ears to bleed.
The idea is not to get carried away with these interesting notes and play them 75% of the time; they would become boring and predictable. Rather, aim for 25-35% of the time. They are ornamental, they embellish an improvisation idea, they do not 'make' it up completely. Use with an awareness of their melodic and interest value.
I'll start with the 9th because this is the most simple and common of the interesting notes. A 9th works with all kinds of chords: a major triad without a dominant or major 7, minor, minor 7th, minor major 7th, augmented... the general feeling of a 9th is to give a 'distant', 'floaty' feeling. The best way to demonstrate the sound of a 9th against these chord types is to play with the left hand a nice simple progression of I, VI, II, V, and repeat... Use the following chord types: IM7, VI(13), IIm7, V+ ... In the key of C, these would be: C, E, G, B / G, C#, F# / D, F, A, C / G, B, D#... What you want to do is listen to the 9th in each of these 4 keys, respectively: D (key of C), B (key of A), E (key of D), A (key of G). These 4 chord types can prove how the 9th, no matter the chord, generally sounds like a distant, floaty chord but it sounds very nice against each. Of course, this discussion revolves around using the 9th in improvisation, not in making the chord nicer, so the use of 9ths here would be part of a longer melodic line involving other notes. It is now up to you to discover what flattening and sharpening the 9th does against each chord to see if you like the effect. Consider chromatic lines, too.
The 11th works lovely against a minor 7th chord, but not well when the chord is major. When the chord is major, use a #11. The problem is that the 11th is the same 'note' as the 4th, so this 3rd / 4th at the same time clashes a bit. Separate them by either playing a major 3rd and a #11 or a minor 3rd with a regular 11th. The sound generated either way is serious, a little dark perhaps, and is a good note to stay on for a few beats whilst you decide where to go after it. Alternating between a 9th and an 11th in a minor 7th chord provides a nice tonal quality.
13ths are also 6ths, but become 13ths because of the presence of a dominant 7th. 7+6 = 13 - remember that. This is the jazzy / bluesy extension and would primarily be involved in an improvisation of blues progressions or swinging jazz numbers with not many minor-type chords. Like the 9th, its quality is a little distant and floaty, but it's jazzy at the same time... a very soft, sexy note value which sounds very nice as the centre-note for an improvisation idea. You can flatten the 13th for a rich sounding chord, but in terms of improvisation, use caution because a flattened 13th is the same 'note' as an augmented so the general quality of this would be 'going up' (usually a 4th) so if you don't intend to 'go up' (a 4th), stay on the 13th. You can't sharpen a 13th because it becomes the same note as the dominant 7th, which is quite useless as you can imagine.
Taking your favourite jazz songs, be excessive with extensions for a few hours just to get used to how they sound... then 'work down' to using safer, more regular notes and only scattering these interesting notes where they feel right to you. As a personal preference, I usually like to begin and end on interesting notes, rather than use them in the middle of an improvised phrase because this highlights them nicely to the listener without drowning them too much.
Hopefully you can have a little fun with this and let me know what you discover.
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Thanks for reading once again !
Posted by danthecomposer