The origins of polyphony: the fusibility theory
The fusibility theory of the origin of polyphony was put forward by the acoustician H.L.F. Helmholtz. It is described here by Bruno Nettl in Music in Primitive Culture, first published in 1956.
Polyphony is found in all corners of the world. Its similarity to various Western European styles cannot, in the vast majority of cases, be ascribed to European influence, nor can remote historical connections with Europe be postulated in most instances. The origin of polyphony has been the subject of many debates and literary discussions. Among the earliest explanations is the theory of fusibility, the result of an experiment in the psychology of music by H.L.F. Helmholtz, the eminent acoustician. The gist of Helmholtz’ theory is that the simpler the mathematical ratio of an interval, the more difficult it is for the human ear to distinguish between the tones of the interval. A great many people can not distinguish between the tones an octave apart; the ratio of an octave is the simplest, 2:1. The number of people who can not differentiate the tones of a perfect fifth, whose ratio is 2:3, is somewhat smaller; fewer still can not distinguish the perfect fourth, whose ratio is 3:4; and so on for the thirds and seconds. Consequently Helmholtz believed that polyphony probably originated when some individuals, incapable of discrimination began singing in perfect fifths, and others, recognising and appreciating the sound for what it was, imitated and initiated a tradition.
Although the theory of fusibility as such has been validated through experiments, the conclusions concerning polyphony that are based on this theory are probably not justified. In some parts of the world, polyphony may have developed according to Helmholtz’ description; such development has been postulated for those cultures using parallel fifths and other kinds of parallel intervals. But it does not explain the origin of other types of polyphony.
Nettl, Bruno, Music in Primitive Culture, Harvard University Press, Cambridge, Massachusetts, 1969, SBN 674-59000-7, p.78