I think linking improvisation to jazz and jazz alone is really limiting; it's why the notion of jam session comes up in the first place. Improvisation has been critical, for example, to much mid-eastern music, as well as Hindustani and some Karnatic musics as well. There are improvisers on all sorts of instruments in all sorts of genres. Part of the difficulty I find is with 'world music' which to me seems to strip improvisational traditions in favor of fairly limited tonal and rhythmic worlds. The result is a narrowly-defined improvisation that too often falls flat. There's also a politics embedded in all of this, I think, since the western tempered scale runs ragged over others; Alain Danielou writes about this.
Jazz may be one set of improvisational styles, but it's not more than that. It often draws heavily on harmony, which is more or less ignored in more than half the world's musics; even rock power chords tend to cut back on harmony. In spite of experimentation, its time signatures are usually 3- or 4- based, and there's figured bass but no drones; drones have their own complexities (with the tambura due to higher harmonic structures and wider tunings than just thirds fourths and fifths etc.). Jazz also has a certain loudness and amplitude envelope. I know what I'm writing here is unbelievably simplified, but I can't see writing a history of improvisation - where the jam session is implicitly called up at the first go.
There's also the history of the blues - blues were often improvised and different verses would be added or subtracted, not even necessarily following themes. The rhythms in some of the delta blues became complex and polyrhythmic; instead of Minton's you had the cutting sessions of the juke joints. There are also banjo, mandolin, and other instrument traditions from the mountains that often involved improvisation, and you can hear this today in Cape Breton's Scottish musics which go back a few hundred years.
Experimentation is everywhere; I play the hegelung, a Philippino instrument from Mindenao. It's been recently electrified and people are experimenting with it in public performance. One of the leading singers in the Philippines, Grace Nono, I knew and her husband has a jazz group using traditional instruments at times. So things come around - and have for centuries. In Hindustani music, the sitar and sarangi are relatively recent instruments for example; in Turkey, the cumbus and all its variants.
The point is, there's no telling at this point, outside of formal composition in the West (and borrowings from the West, for example China), where improvisation ends and composition begins. This isn't world music or fusion, it's deep borrowings or cross-fertilizations, just like the delta blues. One problem with MusicFactory that I don't know how to address, is that most of my contacts are from jazz, and most of the players have that in their background. I don't and I worry about things like volume or how I'd react to 4/4 or free jazz or the traditional envelops of everything from bebop to free. But that's also where the excitement lies for me.
If anyone's interested, I have books on Indian (both Hindustani and Karnatic) music theory, some other stuff as well. I do want to mention by the way that there seems to be a terrific shamisen improvisational tradition - I heard a lot of it in Japan on NHK.
Finally, the N. Indian tradition goes into Pakistan and Afghanistan, where all sorts of amazing complexities and simplifications result - the musics remind me of 'strange attractors' in chaos theory, intensifications around certain themes and instruments, religious and non-religious practices, taksim and raga.
While I really don't know what I'm talking about here, these are the areas I'm interested in pursuing - not to play (I couldn't possibly play traditional sruti or taksim properly - I don't have the hear or the interest/commitment), but to provide inspiration and worlds opening up; while I was working today, I spent the afternoon listening to Nepalese pop music from a couple of stations online.
- Alan Sondheim