The counterpoint music theory is the relationship within a composition where voices are independent in contour and rhythm, but are still interdependent harmonically. It allows for 2+ musical lines that can stand on their own into a composition where they all work together as a whole.
There are two counterpoints to consider in this music theory: first-species and second-species.
What Is First-Species Counterpoint?
To begin a first-species counterpoint, it is necessary to first have a cantus firmus. This is an existing melody that will be used as the basis of the composition. A single new line is composed above or below the cantus firmus. This new line is the counterpoint. It is a new line that will contain one note for every note that is already in the existing melody.
That is why this type of counterpoint is often referred to as 1:1 counterpoint. The melody and the counterpoint will be whole notes.
Beginning a first-species counterpoint means focusing on the creation of a perfect consonance. To achieve this, the first note of a counterpoint is a P1 or P8 below the cantus firmus. If the counterpoint is above, then a P5 may be added in addition to the P1 or P8.
A P5 cannot be used on a lower counterpoint because the tonal context could be misheard by the listener, as the combination would create what is called a “dissonant fourth.”
Some may prefer to use a P12.
Then the final note of a first-species counterpoint should be a P1 or P8, whether it is above or below the melody. This creates a smoother ending that offers listeners some variety to the sound while still providing orientation to the goals of the composition. Different pitches may be considered between the major sixth or minor third in major or minor keys.
The counterpoint should have its own climax and not cross voice with the melody unless it is absolutely necessary. Any voice crossing reduces the independence of each musical line and thus stops the effectiveness of the counterpoint in those locations.
What Is Second-Species Counterpoint?
When creating a second-series counterpoint, the composer must move in half notes against the whole notes of the primary melody. If looking at a composition in 4/4 time, the cantus firmus and first-species counterpoint would be whole notes, while the second-species counterpoint would be half notes.
That is why this type of counterpoint is often referred to as 2:1 counterpoint.
When added to the composition, the listener can pick up the differentiation that the counterpoints create with strong and weak beats. At the same time, the composition begins to include passing tone dissonance. The goal with this counterpoint is to add textural variety, tension to the sound, but with a balance that does not seem harsh or grating to the listener.
A second-species counterpoint must have stepwise motion and a single climax. Because there are added notes to this counterpoint, there must be small steps contained within it so that it doesn’t interfere with the leaps that the melody will be making.
This type of counterpoint will also have secondary climaxes that are employed throughout the composition. That allows the composer to draw certain phrases or expressions within the composition to a logical conclusion. It helps to maintain the integrity of the lines, allowing for the shape of the cantus firmus and the counterpoints so the listener feels like they are listening to a consistent thought instead of multiple tangents.
Unlike with the first-species counterpoint, there are unisons allowed when beginning the second-species counterpoint. It can begin with two half notes in the first bar if desired, but a standard method of adding it is to incorporate a half-beat rest and then including a single half note in the first bar. Using the rest as the initial introduction allows for parsing and makes a composition easier to compose.
Downbeats are always consonant in this counterpoint.
Ending a second-species counterpoint can be either two half notes or a single whole note. This depends on how the composer wants to end the piece.
Why Counterpoint Music Theory is Important to Know
Whether you compose structured or improvisational pieces, music requires movement. The counterpoint music is one effective method that can be used to create the necessary movement by composing three lines in total that can stand independently, but work better together.
Listeners can pick out each expression, while at the same time listening to the entire piece, and this creates a memorable experience.