Typology categorizes objects based on physical properties of a sound, which in essence are gesture types. Morphology describes, in more detail, features of sound objects, down to small timbral and/or textural fluctuations.
In addition to this first sorting, the pitch and harmonic content has to be examined. A class called mass defines if the object has a definite, complex, instable or evolutionary pitch. An object of the categories impulsive, sustained, or iterative might be paired with one with a mass of tonal, complex or varied. Moreover, a suitable object will subsequently be evaluated with respect to its morphological properties such as pitch and/or spectral content, usually referred to as timbral features when fluctuations are small, and as textural features when variations are big. The morphological parameters deal with intrinsic features of a sonic object: Shape, Mass, Grain, Harmonic timbre, and Motion. Schaeffer introduced the two concepts context and contexture: context signifies the large-scale context and contexture signifies the intrinsic features of an object (Chion, 1983, p.61). With these terms, the sonic object became central, with the large-scale context on the one side and faster sub-features on the other. The top-down nature of these concepts enables exploration from overall shape down to fine details of sound objects. Since Schaffer's taxonomy contains more than 50000 different combinations,1.4 it is not appropriate for improvisation. However, taken as an inspiration, and as a way to understand how an improviser is listening during the course of improvisation Schaeffer's ideas are valuable.