Keyboard shortcuts

Press ← or → to navigate between chapters

Press S or / to search in the book

Press ? to show this help

Press Esc to hide this help

1.1 First Species — Note-against-Chord

Definition. First species places one note in the added voice for each chord in the cantus firmus. The added voice plays a chord tone; it does not move melodically within a chord-zone. Voice motion happens only at chord-graph transitions.

What this teaches. First species teaches the student to see the chord-graph as the source of motion. Every voice movement happens because the underlying chord-graph moves, not because the voice elaborates within a static harmony. The student learns to track which chord tones are available at each step and which create good melodic lines.

Setup. A chord-graph path of 4-8 chords. The added voice begins on a chord tone of the first chord and ends on a chord tone of the last chord — preferably the cadential Summit if the path is cadential.

Step-by-step procedure

  1. Identify the chord-graph path. Write out the cantus firmus chord by chord. For each chord, list the four chord tones. Note which orbit each chord belongs to.

  2. Identify common tones across each transition. At every adjacent chord pair, identify which notes are held in common (typically three of four). The common tones tell you what the static options are at each transition.

  3. Identify the moving voice in the cantus firmus. At each transition, exactly one voice in the cantus firmus moves by one semitone. Identify which chord tone changes. This is the cantus firmus’s “active voice” at that moment.

  4. Choose the added voice’s range. Decide whether the added voice sits above the cantus firmus (in soprano range) or below (in tenor range). Above is more common for upper voice lines; below is harder because chord-graph collisions with the bass are more likely.

  5. Pick the first note. Choose a chord tone of the first chord that is in the added voice’s range, not duplicated in the existing voicing. If the cantus firmus already has C-G-D-A in low register and you’re adding a soprano voice, you might pick C5 (chord tone, octave-displaced from the bass C2).

  6. Move chord by chord. At each chord transition, decide:

    • Stay on the same pitch if it is still a chord tone in the new chord (a “common-tone hold”). This is the OTH analog of a pedal note — it shows that the chord-graph moved but the added voice held.
    • Move to a new chord tone that is one or two chord-graph edges away from your current pitch (a melodic step or skip).

  7. Approach the cadence by contrary motion. As the cantus firmus approaches the Summit, the added voice should move in contrary motion (cantus firmus ascending → added voice descending, and vice versa). This honors the OTH “leading-interval-pair” cadence: two voices each moving by one semitone, one expanding a tritone, one contracting an A5.

  8. End on a chord tone of the final chord (preferably a stable one — Summit or Plateau).

  9. Check. Every note in the added voice must be a chord tone of its corresponding chord in the cantus firmus. No exceptions in first species.

Worked example

Cantus firmus (bass + held voicing):

Chord 1: C2-G2-D3-A3      Q777
Chord 2: C2-G2-D3-Bb3     Q877  (A→Bb in voice 4)
Chord 3: C2-G2-Eb3-Bb3    Q787  (D→Eb in voice 3)
Chord 4: C2-G2-D3-A3      Q777  (return — two edges back; via Q877 again)

Wait — chord 4 must connect to chord 3 by a single edge. From Q787 = {C,G,Eb,Bb}, moving to Q777 = {C,G,D,A} requires two changes (Eb→D and Bb→A). That’s two edges. Inserting an intermediate chord 3.5: Q877 = {C,G,Eb,Bb} → {C,G,D,Bb} (Q877; Eb→D) → {C,G,D,A} (Q777; Bb→A). This expands to:

Chord 1: C2-G2-D3-A3      Q777
Chord 2: C2-G2-D3-Bb3     Q877
Chord 3: C2-G2-Eb3-Bb3    Q787
Chord 4: C2-G2-D3-Bb3     Q877  (return through second Plateau)
Chord 5: C2-G2-D3-A3      Q777  (cadence)

Five chords; four single-edge transitions; cadence at chord 5.

Add a soprano voice. Rules: chord tones only; contrary motion to the cadence.

Soprano analysis:

ChordAvailable chord tones (in soprano range)ChooseReason
1G4, A4, C5, D5G4Stable opening; low end of range
2G4, Bb4, C5, D5Bb4Step up; chord tone (the A→Bb change moves in soprano too — but here we’re in the upper voice, not voice 4)
3G4, Bb4, C5, Eb5C5Step up; common tone with chord 2
4G4, Bb4, C5, D5D5Step up to peak
5G4, A4, C5, D5A4Contrary motion descent to cadence — D5 → A4 is a P5 leap, but in OTH that’s a structural-fifth descent, totally appropriate at the cadence

Soprano line: G4 → Bb4 → C5 → D5 → A4.

Check. Each note is a chord tone. The line ascends G4→Bb4→C5→D5 (three stepwise moves) and descends to the cadence A4 (a structural-fifth leap downward). Contrary motion at the cadence: the cantus firmus’s last edge is Bb→A (descending semitone in voice 4); the added voice’s last move is D5→A4 (descending fifth). Both descend — so this is similar motion, not contrary. To get contrary motion, the added voice should ascend at the cadence: e.g., end on D5 → C5 (descending whole step) instead of D5 → A4. But wait — the cantus firmus’s voice 4 moves Bb→A (descending), so for contrary motion the added voice should ascend. Let me revise:

ChordChooseReason
1C5Open on the tonic
2C5Common-tone hold
3C5Common-tone hold
4C5Common-tone hold
5C5Common-tone hold

This is too static. Try again:

ChordChooseReason
1C5Open on the tonic
2Bb4Step down; chord tone (parallels the cantus firmus’s A→Bb)
3Bb4Common-tone hold
4Bb4Common-tone hold (cantus firmus moves Eb→D underneath)
5A4Cadential descent — but this is similar motion with cantus firmus’s Bb→A

Hmm. The cantus firmus’s last edge Bb→A is a single voice descending; for the added voice to move in contrary motion at the cadence, it needs to ascend or stay. Let me make the soprano line:

Chord 1: D5
Chord 2: D5  (held — common tone)
Chord 3: Eb5 (step up — chord tone)
Chord 4: D5  (step down — chord tone; contrary to soprano-4-Eb5)
Chord 5: A4  (descent to cadence — structural P5 descent; cantus firmus also descends; SIMILAR motion)

The OTH cadence resolves Q877→Q777 with one voice moving Bb→A (single descending semitone). For the added voice to have contrary motion at the cadence, it must ascend or hold. Holding D5 across chord 4 → chord 5: but D is in both Q877 and Q777, so this is a common-tone hold:

Chord 1: D5
Chord 2: D5  (common-tone)
Chord 3: Eb5
Chord 4: D5
Chord 5: D5  (common-tone hold — contrary motion is *oblique*)

This is a clean first-species line. The cadence is reached via oblique motion (added voice holds D5; cantus firmus moves Bb→A). The added voice traverses D5 → D5 → Eb5 → D5 → D5 — a single neighboring excursion to Eb5 and back. Plain but legal.

Common errors in first species

  1. Non-chord tones. First species requires every note to be a chord tone. Slipping in a passing tone (which is allowed in second species but not first) is the most common error.

  2. Parallel motion across multiple chord-graph edges. If the added voice moves in lockstep with the cantus firmus’s moving voice across multiple transitions — both ascending or both descending by one semitone each time — you create the OTH analog of parallel-fifth motion. In first species, prefer contrary or oblique motion at every transition.

  3. Failing to land the cadence. The added voice should end on a chord tone of the final chord, ideally the root of the cadential Summit (or its octave). Ending on an inner chord tone (like A4 over a C Summit) is acceptable but feels less “settled.”

  4. Voice crossing. The added voice should not cross below the cantus firmus’s top voice. If your added voice is in soprano range, watch out for moments when the cantus firmus’s voice 4 ascends into your range.

  5. Static line. A first-species line that holds the same pitch for all five chords is technically legal (every note is a chord tone) but pedagogically boring. Aim for at least one melodic step or skip somewhere in the line.