Third-Species Counterpoint

Third-species counterpoint places four notes against each cantus firmus note, creating a 4:1 ratio. The counterpoint typically moves in quarter notes against a cantus in whole notes. With four beats per measure, only the first beat (the downbeat) must be consonant; the remaining three beats may contain dissonances, provided they are used as passing tones or neighbor tones approached and left by step.

The increased rhythmic density introduces a new melodic embellishment: the cambiata (changing-note figure), a four-note pattern that dips to a dissonant note by leap and then resolves — a special exception to the rule against leaping to a dissonance. The double neighbor tone also appears in third species, circling around a central pitch with two stepwise dissonances. These figures are idiomatic in 16th-century style and should be recognized as stock gestures rather than rule violations.

Managing the melodic contour becomes more demanding with four notes per measure. The line should have a clear direction, avoid excessive repetition, and use a mixture of stepwise motion and carefully placed leaps. Leaps should generally be small (a third or fourth) and should be compensated by motion in the opposite direction. The forbidden parallels between downbeats remain in force, and the voice should avoid outlining dissonant harmonic intervals over a span of beats even when each individual note is handled correctly.