Section 30.5 Fourth Species Counterpoint
Fourth species deals with writing suspensions (and syncopations). Because this is only a brief introduction to species counterpoint, you will only encounter the cantus firmus in the lower voice in fourth species in this text. See the fourth species rules below.
Start with a half rest, then write a half note an 8ve above the cantus firmus. The half note on the 3rd beat of every measure but the penultimate one ties across the barline to a half note on the first beat of the succeeding measure.
End on a whole note at the interval of an 8ve above the cantus firmus.
The penultimate measure should contain a 7-6 suspension.
The half note on the third beat of each measure is always a consonance.
If the half note after a tie is a dissonance (4th or 7th), it is a suspension and must resolve down by step.
Allowable suspensions in the upper part are 4-3 and 7-6; 9-8 and 2-1 are not allowed.
If the half note after the tie is a consonance (1, 3, 5, 6, 8), it is a syncopation and can be left in any manner (by step or leap in any direction).
Notice that all suspensions and syncopations are labeled and all dissonant intervals are circled.