Figured Bass Realization: Handling a 4–3 Suspension Over a Changing Bass
A student realizes a figured bass in four voices. The bass line reads: F (with figure 6), B♭ (with figure 5/3), then a passage marked 4–3 over a sustained G in the bass, then C (with figure 6/4), then F (5/3). The key is F major. Over the sustained G, the student writes the chord G–B♭–D and then, on the resolution, G–B♭–C, treating the C as the resolution of the suspension. The instructor marks the resolution as incorrect and says the student has confused the suspension's preparation and resolution and has also created a doubled leading tone elsewhere. The student insists the C is the resolution because "4 resolves to 3."
1. Explain what a 4–3 suspension over a bass note requires, and identify the student's error.
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A 4–3 suspension means the interval above the bass is a fourth on the strong beat (the suspension), resolving down by step to a third on the weak beat (the resolution). Over a bass G, a fourth above is C, and a third above is B (or B♭ depending on key). The suspension must be prepared as a consonance in the preceding chord (the C must be sounded as a chord tone or consonant interval before it becomes the dissonant fourth), then held over the bass change (the suspension), then resolved downward by step to the third.
The student wrote G–B♭–D as the chord and then G–B♭–C, which reverses the figure: they placed the fourth (C) on the resolution and the third (B♭) on the suspension. That is a 3–4 retardation, not a 4–3 suspension. The correct realization over G is: suspension chord contains C (a fourth above G) on the strong beat, resolving to B♭ (a third above G) on the weak beat, with the C prepared in the previous chord. In F major, B♭ is diatonic, so the resolution is G–B♭–D (a G minor triad, ii in F). The student's version produces a G–C–D–B♭ sonority that is not the intended harmony.
2. The instructor also mentions a doubled leading tone. Where in this progression is a leading tone most likely to be doubled, and what rule governs its doubling?
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In F major the leading tone is E. The most likely place for a doubled leading tone in this bass line is the final F (5/3) chord, where the student may have voiced E in two upper voices (e.g., alto and tenor both on E) while the bass is F. The rule: never double the leading tone in a dominant-function chord, because the leading tone has a strong tendency to resolve up to the tonic; doubling it forces one voice to resolve up and the other to break the tendency (often producing parallel octaves or an unresolved tendency tone). In a V chord, double the root or the fifth, not the third if the third is the leading tone. In a V7, the leading tone appears once and resolves up; the seventh resolves down.
Check the C (6/4) chord as well: in F major, a 6/4 on C is a cadential 6/4 (C–F–A), which contains no E, so the doubled leading tone is unlikely there. The likely culprit is the final F chord if the student harmonized the approach with an E in two voices, or the B♭ (5/3) chord if the student mistakenly treated E as a chord tone. The fix: respell the final chord as F–A–C with F doubled (root doubling), and ensure any E appears in only one voice and resolves to F.
3. The student argues "4 resolves to 3" as a universal rule. Refine that statement so it is accurate for suspensions and distinguish it from retardation.
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The accurate statement is: in a 4–3 suspension, the fourth above the bass is the dissonant preparation-suspension and resolves down by step to the third above the bass on the weaker beat. The figure describes the interval above the bass, not a chord-tone identity. The fourth is dissonant against the bass and must be prepared as a consonance in the preceding chord and resolved downward by step.
A retardation is the mirror image: the resolution is delayed upward, e.g., a 7–8 or 2–3 figure where the dissonance resolves up. A 3–4 figure would be a retardation-like motion where the third resolves up to a fourth - not a standard suspension. The student's realization (third on the strong beat, fourth on the weak beat) is a 3–4 retardation pattern, which is why the instructor called it a confusion of preparation and resolution. The refinement: the numeral pair always reads suspension interval first (strong beat), resolution interval second (weak beat), and the direction of resolution is downward for suspensions (4–3, 7–6, 9–8) and upward only for retardations (2–3, 7–8). The student should also verify preparation: the C must be consonant in the chord before the G bass arrives.