To me, improvisation is an expression of an attitude. When improvising freely in a band I go in with (hopefully) and attitude that is going to allow for interesting dialogue. I guess for it to be dialogue the most important thing is to listen alertly to what other people are saying, respond with taste and also say intelligent things myself. Those three main areas are complex things in themselves. Listening alertly means hearing what other people are doing and hearing what I myself am doing and being ready to act with a relevant responce. Responding with taste requires a certain amount of subtly in adding to the overall sound by playing a role that compliments the other players approach to the overall sound. The right time to step in and make a statement of one’s own is a hard thing to judge. No one likes greedy improvisers and we all know when it’s going on. It’s just hard to explain and deal with when that situation arises. Sensitivity, a taste for structure, contrast and interest is what should drive the decision to ‘step in’.
A lot of what I improvise is so called ‘non-tonal’ music. That’s just because it’s what I (and my fellow musicians) usually hear and like. But improvising freely should not rule out the major scale. Really, it should not rule out anything. In fact, for free improvising everything should be taken into consideration. The reason ‘personality’ seems to be such a big part of the avant-garde is because of all the amazing combinations of our influences that come out when we are improvising. There is something quite unique about how a jazz drummer (with his understanding of what ‘swing’ is) can play a rock beat (with his understanding of what ‘grunge’ is). This is but one example of a whole spectrum of things – which is why we should study our favourite classical composers, listen to metal bands, do gigs with folk vocalists and go and see what modern be-bop players are doing, because it all counts towards what we are as a musician who makes music by improvising.