Counterpoint is the art of combining independent melodic lines so they sound clear, balanced, and expressive together. This cheat sheet helps Grade 11-12 music theory students review the basic rules used in species counterpoint, invertible counterpoint, and fugue writing. These ideas are important for analyzing Baroque music, composing short studies, and understanding how composers create complex textures from simple motives.
The core concepts include consonance and dissonance, melodic independence, voice-leading rules, and imitation. Species counterpoint builds control one rhythm layer at a time, while invertible counterpoint tests whether two voices still work after switching positions. Fugue basics focus on how a subject is introduced, answered, developed through episodes, and combined in entries such as stretto.
Key Facts
- In first species counterpoint, each note in the counterpoint sounds against one cantus firmus note, and vertical intervals should be consonant.
- Perfect consonances are unison, octave, fifth, and sometimes fourth depending on context, while imperfect consonances are third and sixth.
- Avoid parallel perfect fifths and parallel octaves because they weaken the independence of the voices.
- In second species counterpoint, two notes sound against each cantus firmus note, and the strong beat should normally be consonant.
- A passing tone is a stepwise dissonance that moves between two consonant tones in the same direction.
- In invertible counterpoint at the octave, an interval number changes by the rule original interval + inverted interval = 9, such as 3 becoming 6.
- A fugue subject is the main melodic idea, and the answer is the subject restated in another voice, usually at the dominant or tonic level.
- A stretto occurs when a new subject entry begins before the previous subject entry has finished.
Vocabulary
- Counterpoint
- Counterpoint is the combination of two or more independent melodic lines that fit together harmonically.
- Cantus Firmus
- A cantus firmus is a fixed melody used as the foundation for writing counterpoint.
- Species Counterpoint
- Species counterpoint is a step-by-step method for learning counterpoint through controlled rhythmic patterns.
- Invertible Counterpoint
- Invertible counterpoint is counterpoint designed so the voices can switch positions and still sound correct.
- Fugue Subject
- A fugue subject is the main theme that is introduced and imitated throughout a fugue.
- Episode
- An episode is a passage in a fugue that develops motives from the subject or countersubject between full subject entries.
Common Mistakes to Avoid
- Using parallel fifths or octaves, which is wrong because both voices move together in a way that destroys their independence.
- Treating every fourth as automatically consonant, which is wrong because a fourth above the bass is often considered dissonant in strict counterpoint.
- Placing a dissonance on a strong beat without preparation or resolution, which is wrong because dissonance usually needs controlled voice leading.
- Writing an invertible counterpoint line without testing the inversion, which is wrong because some intervals that work in one position may become problematic after inversion.
- Calling any repeated imitation a fugue, which is wrong because a fugue has organized subject entries, answers, episodes, and developmental procedures.
Practice Questions
- 1 In invertible counterpoint at the octave, what interval does a 3rd become after inversion?
- 2 A counterpoint line moves from C to D to E while the cantus firmus holds C, with D as a passing tone. Is D consonant or dissonant against C?
- 3 Identify the problem if two voices move from C-G to D-A in the same direction and keep the interval of a perfect fifth.
- 4 Explain why a fugue needs both melodic independence and recognizable repetition of the subject.
Understanding Counterpoint & Fugue Basics
Species exercises work because they limit your choices. When rhythm becomes more active, the ear starts to hear two different kinds of events. Notes on strong beats carry more structural weight.
Notes between them can create motion. In third species, four notes may move against one longer note. In fourth species, a note is held across the bar line, creating a suspension.
The held note may clash at first, but it must have been stable before the clash and then move down by step to a stable note. This pattern gives dissonance a clear cause and a clear resolution.
Good counterpoint is not made by checking vertical intervals alone. Each line must still sound like a believable melody when sung by itself. Large leaps need careful handling, especially if several occur in the same direction.
Stepwise motion helps a line recover after a leap. Contrary motion, where one voice rises while another falls, often keeps the parts distinct.
Similar motion is useful too, but it needs attention near perfect intervals. Students should listen for moments when both lines seem to merge into one outline rather than sounding like two separate musical thoughts.
Invertible counterpoint is a practical test of planning. A lower voice may become the upper voice, so every interval must remain acceptable after the exchange. Thirds become sixths, while seconds become sevenths.
Fifths remain fifths when inversion occurs at the octave, which makes them more delicate than they first appear. The musical result can change even when the notes are correct.
A line that sounded strong in the bass may feel heavy or awkward above another line. Composers therefore consider range, balance, and where the main melody will be heard before they decide that a passage is truly invertible.
A fugue grows from the character of its subject. A subject with a clear rhythm, a memorable interval pattern, and a definite ending is easier to recognize when it returns in different voices. The answer may be real or tonal.
A real answer copies intervals exactly at a new pitch level. A tonal answer adjusts some intervals so the music stays firmly connected to the home key.
While one voice presents the answer, the first voice may continue with a countersubject. If that continuation returns repeatedly against later entries, it becomes an important second idea rather than simple accompaniment.
Episodes give the listener a break from full subject statements. They often use a small fragment from the subject or countersubject, then sequence it through several pitch levels. This creates movement toward a new key area.
Later sections may use inversion, augmentation, or diminution. Inversion turns rising shapes downward and falling shapes upward. Augmentation makes note values longer.
Diminution makes them shorter. When analyzing a fugue, mark each entry, name its voice, and note the key area. Then listen for how overlap, contrast, and returning motives control the sense of direction.