Questions: Outer Voice Independence: Soprano and Bass Relationship

Question 1

Both the soprano and bass move upward by a fifth simultaneously (bass from C to G, soprano from G to D). What rule does this violate, and why is it a problem?

• A. It creates parallel fifths between the outer voices, making them sound like a single entity and destroying their independence
• B. It creates similar motion, which is only allowed between inner voices, not the outer voices
• C. Moving both voices by the same interval is prohibited in any form of voice leading
• D. The soprano should never move by a fifth — only stepwise motion is acceptable in the outer voices

Answer: (A)

Parallel fifths between soprano and bass are one of the most serious voice-leading errors: consecutive perfect fifth intervals between the outer voices strip both of their harmonic distinctiveness and make them sound like a doubled single line rather than two independent voices. Option B is wrong — similar motion is acceptable for outer voices, just handled carefully. Option C is too broad; it is not the same interval that is the issue but the parallel perfect consonances. Option D is false; leaps are fine in the bass and soprano.

Question 2

A composer wants to write a strong progression from I to V in a major key. Which outer-voice motion best reinforces harmonic independence?

• A. Soprano moves up by step (scale degree 3 to 5); bass moves down by a fourth — contrary motion
• B. Soprano and bass both move upward by a step — parallel motion reinforcing the harmonic direction
• C. Both voices hold their pitches — oblique motion preserves the existing sound
• D. Soprano leaps up by an octave; bass moves up by a third — similar motion in the same direction

Answer: (A)

Contrary motion — soprano and bass moving in opposite directions — creates the strongest sense of two independent melodic lines and is the gold standard for outer voice writing. Option B (parallel motion) risks parallel octaves or fifths and reduces the sense of independence. Option C (both holding) is oblique motion, valid but creating no harmonic direction — unsuitable for a progression. Option D (both moving upward) is similar motion, acceptable occasionally but not preferred. Contrary motion at a I–V progression gives maximum clarity and independence.

Question 3

Parallel octaves between soprano and bass are less problematic than parallel fifths because octaves represent the same pitch class and therefore preserve harmonic identity.

• T. True
• F. False

Answer: False

Parallel octaves between soprano and bass are equally prohibited and equally problematic. When soprano and bass move in parallel octaves, they effectively double a single melodic line — the two voices sound like one, eliminating the independence that makes four-part writing work. Parallel octaves are if anything more destructive than parallel fifths: an octave is a perfect consonance that completely merges the two voices into a unison sound class, whereas a fifth at least produces a distinct harmonic interval.

Question 4

The soprano and bass together form the harmonic skeleton of four-part writing; the alto and tenor fill in what the outer voices define.

• T. True
• F. False

Answer: True

This is precisely the structural relationship in four-part writing. The soprano is the most audible voice (highest pitch); the bass is the most harmonically defining (determines root position vs. inversions). Together they create the frame that listeners hear most immediately and that defines the harmonic content. Once the outer voices are correct — with appropriate independence, consonant intervals, and good melodic motion — placing inner voices becomes a more constrained and manageable task. Problems in the outer voices cannot be fixed by the inner voices.

Question 5

Why is contrary motion between soprano and bass considered the gold standard for outer voice independence, and what does it achieve that parallel motion cannot?

Model answer: Contrary motion — soprano and bass moving in opposite directions — creates two genuinely independent melodic lines: when one rises, the other falls, producing a sense of expansion or convergence that registers as harmonic direction. Parallel motion, by contrast, moves both voices in the same direction, making them sound like aspects of a single entity rather than two separate voices. The risk of parallel motion is also practical: it easily produces parallel fifths or octaves, the most serious errors in counterpoint. Contrary motion is kinetically clear and minimizes those risks.

The value of outer voice independence is not merely technical compliance — it is what makes the harmonic texture feel alive. A soprano rising while the bass falls creates a sense of expansion; the reversal creates convergence. These physical directions give progressions their sense of arrival, departure, and tension. Parallel outer voices feel static or mechanical by comparison. This is why analyzing soprano–bass two-voice counterpoint is often the first step in studying a chorale: if the frame is strong, the inner voices almost fall into place.