Diaphony or Organum consisted of a succession of fourths or fifths and octaves, thus:
Two Parts Three Parts
It has been denied by some authorities that such a barbarous manner of singing ever existed; but two considerations have been lost sight of, in making this denial: First, the fourth, fifth and octave were esteemed the only consonances. Secondly, the undisputed fact that as late as the time of Chaucer, if not later, what was called “discanting quatible” or “quinable” existed; this discanting was done as follows: The performer while singing a melody accompanied himself on the lute, playing the same melody a fourth or fifth above. It can hardly be doubted that a style of performance that was esteemed in the 15th, was perfectly satisfactory to the ears of the 10th century.
Discant.—Another early attempt at harmonic effect was the singing of an extemporaneous part or parts with the melody, called Discanting. In course of time the Discant or Organum gradually crystallized into rules, and other intervals were accepted. Strangely enough, dissonances seem to have been admitted with great freedom, and thirds and especially sixths, were avoided. The only dissonance that was not allowed was the minor second.
The New Organum.—In the 11th century, a method of combining sounds, called the New Organum, was developed. This kind of Organum admitted thirds and sixths. The following example will sufficiently illustrate this:
