Frank--

Sorry to have taken so long to get back to you, but recent cold snap, coupled with the flu have kept me away from the computer--I found your thoughts to be very interesting--here are some thoughts of my own--

The subject of improvisation is big, as you point out,there are so many different ways that it can be approached--Melodic, rhthmic, harmonic, as well as by way of the different types of counterpoint.

The differences between styles of jazz is, at least in part, in the approach to improvisation, and there are many, many, non-jazz based styles of improvisation as well.

In a way, composition is really basically improvisation, and the great classical masters tended to be great improvisors, and the great jazz players have tended to be great composers, as well.

Improvisation was a weak point in my playing for many years, and as a result, I've spent a lot of time trying to figure out what the spontaneous players were doing that I wasn't, and how to approximate it--

One of the things that I discovered from reading what players had written, and musicians who were both willing and able to talk, is that
a player has to have a handle on three elements--the rhythmic phrases that are appropriate, melodic material (such as the melody itself, and the scale that it uses), and structure of the tune that is the backdrop for improvisation--

My approach to improvisation is to begin with rhythmic phrases and cadences, then to impose the appropriate scales over them. The trick, at least for me, to teaching blues, is simply to teach the way that call and response works within the blues progression, and then to help them to find a rhythmic phrase that they "feel'"--

I am talking about soloing here, though, and I just realized it--much of the real improvising in folk/blues/jazz/pop is really in creating the accompaniment, it works with the same elements, though--


By the way, I think it is, at least from a creative point of view, easier to improvise over that Db7Aug11 chord than over a Bluegrass C triad, since there are many more things that you can play over the Db7Aug11 and still stay within the harmonic style.