D Dorian
Half notes displaced by half a measure — struck on the weak half and held across the barline. The final measure is a whole note.
Cantus firmus: Fux, Gradus ad Parnassum (Figure 144) — 11 measures
Your line: written above the cantus firmus
To pass: complete every measure with no rule violations and score at least 75/100
How Fourth Species works
Place your notes on the second half of each measure. To tie a note across the barline, place a whole note (duration 4) starting on the weak half — it will sound through the next downbeat.
When the held note becomes dissonant at the downbeat, you have a suspension: it must have been consonant when struck (the preparation) and must resolve downward by step to a consonance.
The classic chains: 7–6 and 4–3 when writing above the cantus firmus, 2–3 when writing below.
If no suspension is available, break the syncopation briefly: strike a consonant half note on the weak beat without tying it.
The rules
- Suspensions: prepare, suspend, resolve down by step. A dissonance on a downbeat is only allowed when it is held over from a consonant preparation and resolves down by step to a consonance.
- Struck notes must be consonant. Any note you strike (rather than hold) must form a consonance with the cantus firmus.
- Keep the syncopated rhythm. Fourth species lives off the barline: most notes should be struck on the weak half of the measure and tied over.
- Begin and end on a perfect consonance. The first and last intervals must be a unison, perfect fifth, or octave against the cantus firmus (a fifth below the CF is not allowed when writing underneath it).
- No parallel or hidden fifths and octaves. Two voices may not move in the same direction into a perfect fifth or octave. Consecutive perfect intervals of the same size destroy voice independence.
- Singable melodic intervals only. No melodic tritones, sevenths, or leaps larger than an octave. Your line should be singable.
- Recover from leaps by stepping back. After a leap (especially a large one), change direction and move by step to fill in the gap.
- Aim for a single climax. Your line should have one highest note, ideally somewhere in the middle of the phrase.
- Keep the line varied. Avoid long chains of parallel thirds or sixths, and avoid mid-phrase unisons with the cantus firmus.
- Prefer contrary motion. Moving against the cantus firmus keeps the two voices independent. Aim for contrary motion at least ~40% of the time.
Tips
- • Chains of suspensions (7–6, 7–6, 7–6…) are idiomatic — descend one step per measure.
- • The preparation must be at least as long as the suspension: use whole notes starting on the weak beat.
- • End with the classic clausula: a suspension resolving into the final perfect interval.