When jazz musicians first learn to play chromatically in melodic improvisation, it is often limited to the chromatic vocabulary that is integral to the jazz language, and, for some players, it can be difficult to explore beyond that. I'm going to lay out a simple concept that will hopefully give us more approaches to melodic chromaticism.
When I say melodic chromaticism, I have a specific definition. I am not referencing chord substitutions or scale substitutions like a tritone sub or the half-whole diminished scale on a dominant chord. I am referencing a more specific concept, and that is how specific chromatic notes relate to the diatonic chord/scale they are presented on. A simple example would be how the note D-flat relates to the mode C mixolydian (C7). I'm asking questions like where can D-flat go? How can I use the note D-flat in context of C mixolydian?
What are the Chromatic Tones and Tension Tones?
A basic approach that helped free me up when approaching melodic chromaticism, is to focus on the chromatic and tension notes as a set of options instead of focusing mainly on the chord tones or notes of the scale, which are beyond memorized at this point anyhow. On a C7 what are your chromatic options or other dissonant options? Assuming that the sus4 color is not being employed, the dissonant tones will be D-flat, E-flat, F, A-flat and B. You might raise an eyebrow at the F, but, though the F is diatonic to C mixolydian, it is definitely a dissonant note or, in other words, a tension tone. F-sharp has not been included in our list because, though it is chromatic to the key, it can be used as consonant note over the chord or a tone of resolution (the sharp 11). E-flat and F are also both blues notes when C7 is a tonic chord, like in a C blues or over an extended C7 vamp, which means you can use E-flat and F as dissonant resolution tones when invoking a blues color in those contexts. Below you can see the mode C mixolydian on the left (the chord tones for C7 are hollowed out), and on the right you can see the chromatic and tension tones.
How do they Resolve?
The next question is where do all of these chromatic or tension notes resolve? Following is a graphic of all the resolutions by step, with the dissonant tone first and then a possible resolution. (blues note resolutions are indicated).
You should also think of these option in context to the key. So, when C7 is a tonic like in a C blues, then you have the blue note options shown above, but if you are on a C7 in a standard tune where the key center is F, then those blue notes option change to match the the key of F. The feeling or color of the other chromatic/tension tones will also subtly change depending on your key center.
Applying it in Improvisation
By focusing on the dissonant tones as a basic set of options you are able to approach them in a variety of ways. You can use them as passing tones in a scalar passage, as neighbor tones, as appoggiaturas (dissonances approached by a leap), or various combinations of these. I would suggest improvising in a vamp setting over a single chord as exploring all the option I just listed. In a future article I'll go more in depth into these melodic gestures.
I have given you the options over C7/C Mixolydian, but each chord/scale will have its own unique dissonant tones and resolutions which I encourage you to explore and memorize them. In the next few weeks look for more articles including a couple easy techniques to improve altissimo and overtones.