Bits on improvisation

Quick hit: from a response to a colleague's query about the difference of fact or terminology between "improvisation," "aleatoric music," and "chance" music. Here's what occurred to me:

I would not equate the them. With the exception of just one or two genres, I would submit that most improvisation happens within the constraints of a stylistic vocabulary or set of expectations: jazz, blues, Indian, Near Eastern, etc all have their own expectations. The exceptions that occur to me are (a) free jazz (though that wound up having its own, relatively narrow set of expectations) and (b) so-called "free improvisation"--I'm thinking here of the English people like Derek Bailey, etc.

Improvisation in most genres I know is more about the spontaneous selection and combination of a musical vocabulary, and usually involves some combination of pre-existing and spontaneously-composed materials. Hence, it's not "by chance".

When I'm describing "chance music" (the term I prefer) to undergrads, I usually will describe what I have seen as two parallel tendencies in Euro-American art music: music where the "chance" element occurs in the stage of composition (Cage using dice, I Ching coins, or the imperfections on a set of manuscript paper), versus those where the "chance" element occurs in the act of performance, typically by performers who are permitted such choice by composers. I don't even think that the latter is "by chance", because most performers' biggest problem, regardless of the strictures of a given composition, is that they tend to fall into familiar patterns. The biggest challenge in playing "free" (-jazz, for example) is how to AVOID falling into such patterns.

Derek Baily wrote a really great book on this: Improvisation: Its Nature and Practice in Music.

Improvisation, typically, is intentional and, in most situations, idiomatic. There's very little left to "chance" about it--except the mistakes. Cue the old joke-definition of jazz: e.g., "two wrong notes in a row".