The control of acoustic intensity during jazz and free improvisation performance : possible transcultural implications for social discourse and community

This paper demonstrates the predominance of a pattern of acoustic intensity change in recorded improvisations in which intensity rises are shorter than falls and in which the rate of intensity change is greater in the rises than in the falls. A wide range of improvised music from the USA, Europe, and Australasia is studied, and the analyses are conducted by measuring intensity in moving windows across each piece. The windows used are 0.04 sec, 0.5 sec, 5 sec, and 10 sec, chosen to sample a range of important musical structures such as patterns, phrases, and phrase groups. In addition, a comparative analysis uses detected rhythmic beats as the window, with slightly variable lengths. The recurrent pattern is interpreted in terms of a hypothesised Force-Effort-Energy-Loudness-Affect (FEELA) chain, linking improviser with listeners and with other improvisers. Partial experimental investigation of this chain in other work has been consistent with the theory in supporting a major role of acoustic intensity in the perception of both musical change and affect. It seems that improvisers share this patterning of acoustic intensity with interpreters of classical music, and composers of electroacoustic music. Thus we suggest that music made with non-acoustic instruments—that is those for which physical effort of performers does not provide the energy comprised in a sound— has developed the same pattern because composers and improvisers recognise its expressive power as a statistical archetype. Improvisers are particularly salient to this argument because they are not necessarily constrained by any of the prior conventions of music. It remains to be seen whether this statistical feature could have been assimilated from environmental and/or speech sounds. Given that the studied music flows within both the Afro-logic and Euro-logic discourses delineated by George Lewis, we discuss the possible trans-cultural implications of our observations for social discourse and community.