Good evening everyone. This is my first post on the blog, so a little about me: I'm an Italian saxophone player from a small town near Bari, in Puglia, and I'm in my seventh year at the conservatory.

Today I want to ask you a question about music.

Last summer I attended the Jazz Summer Workshop in Siena. My teacher of musical form analysis, Stefano Zenni, gave a class on George Russell, one of jazz's most mercurial arrangers, composers and theorists. These days I'm reading Russell's "Lydian Chromatic Concept of Tonal Organization."

Here's what I keep noticing. When teaching how to play over II-7 / V7 / Imaj7, many teachers tell students to just play the I major scale over all three chords. For example, over D-7 / G7 / Cmaj7 they play C major. It's a quick way to stay in the right key, but it also makes them play a natural 11 over a dominant (or major) chord.

Reading Russell, I saw he thought differently. In a nutshell: a major 9th chord with a ♯11 has a greater degree of unity than the same chord with a natural 11. So we can take the Lydian scale as our "parent" scale, and over that example we'd play in C Lydian (the notes of G major) rather than plain C major.

All of this set off a question I still can't resolve.

If I write a dominant chord, say C7, I treat the seventh as a flat seventh. I don't have to write C7♭. But if I write C11, I treat the eleventh as natural, and I have to specify when I want it flat (C11♭) or sharp (C11♯). The same goes for the 9, the 13, and so on. Why? Why is only the seventh assumed to be flat?

I asked several teachers. They always gave the same answer: because the first seventh in the overtone series is a flat seventh. But if we follow the overtone series, the first fourth in it is a sharp fourth. By that logic I should also treat the eleventh as a sharp eleventh by default.

So my question is still unresolved.