AP Music Theory part-writing and voice leading: the rules examiners score in the free-response section

Why part-writing decides the free-response section

Part-writing (also called voice leading) is the most rule-bound task on the AP Music Theory exam, and it appears twice in the free-response section: once realizing a figured bass and once realizing a chord progression given as Roman numerals. Unlike a listening question, where you either hear it or you do not, part-writing is scored against a fixed checklist of rules. That is good news: if you internalise the rules and a reliable order of operations, the points are highly recoverable. This guide states every rule in words and scale degrees, because the exam itself is written on the staff and you must be able to picture it without an image.

These skills build directly on the fundamentals: secure major scales and scale degrees, major keys and key signatures, half steps and whole steps, and confident pitch and pitch notation.

The four voices and their ranges

Four-part writing uses soprano, alto, tenor and bass, written on a grand staff with soprano and alto sharing the treble staff (stems up for soprano, stems down for alto) and tenor and bass sharing the bass staff (stems up for tenor, stems down for bass).

• Soprano: roughly middle C up to the G or A above it.
• Alto: roughly the G below middle C up to the D above it.
• Tenor: roughly the C an octave below middle C up to the G above it.
• Bass: roughly the F or E below the tenor up to about middle C.

Keep each voice inside its range, and never let two voices cross (an upper voice dipping below a lower one) or overlap (a voice moving past where the neighboring voice just was).

Spacing and doubling

The banned parallels

The single most penalized category of error is parallel perfect intervals.

Tendency tones: the leading tone and the seventh

Two notes have a fixed destination, and resolving them correctly earns easy points.

The leading tone is scale degree seven, a half step below the tonic. In an outer voice, and always at a cadence, it resolves up a half step to the tonic (degree eight or one). The chordal seventh, the note a seventh above the root of any seventh chord, resolves down by step to the third of the next chord. For a dominant seventh chord (V7) in a major key, the seventh is scale degree four, which falls to scale degree three.

Reading figured bass and Roman numerals

A figured bass gives you the bass note plus small numbers showing the intervals to stack above it. A bare bass note (or a "5 over 3") means root position; a 6 means first inversion (a sixth and a third above the bass); a 6-4 means second inversion; for sevenths, 7 is root position, 6-5 first inversion, 4-3 second inversion, and 4-2 (or just 2) third inversion. An accidental beside a figure (or a slash through it) raises that interval, which is how the raised leading tone appears in minor keys.

A Roman numeral names the chord by scale degree and quality: uppercase for major (I, IV, V), lowercase for minor (ii, vi), a small circle for diminished (vii with a degree symbol), and added figures for inversion and sevenths, exactly as in figured bass. The numeral tells you the function; you choose the spacing.

A reliable order of operations

Doing the voices in the right order prevents most errors before they happen.

1. Label the key and the chords. Confirm the key signature, then write or confirm the Roman numeral under every bass note so you know each chord's members.
2. Write the bass. From the figured bass it is given; from Roman numerals, choose the bass note that the inversion requires.
3. Write the soprano. Aim for a smooth, mostly stepwise line that uses chord tones and shapes a sensible melodic arch.
4. Fill the inner voices. Add alto and tenor from the remaining chord tones, moving each voice by the smallest interval and keeping common tones where possible.
5. Resolve tendency tones and check. Resolve the leading tone up and every chordal seventh down, then scan for parallel fifths, parallel octaves, voice crossing, overlap and spacing faults.

A worked realization in words

How examiners award the marks

The part-writing questions are graded against a rubric that gives credit for correct chord spelling, correct inversion from the figure, correct doubling, resolved tendency tones, and the absence of parallels and range or spacing faults. You are not asked to be musically inspired; you are asked to be correct. Because each error type is listed separately, a single slip rarely sinks the whole question, so always finish the realization even if you are unsure of one chord, and always do the final parallel check, as it is the cheapest set of points on the paper.

Try this

Q1. In a dominant seventh chord in G major, name the leading tone and the chordal seventh by letter and state how each resolves. [2 points]

• Cue. The leading tone is F sharp (degree seven), which rises a half step to G; the chordal seventh is C (degree four), which falls by step to B (degree three of the tonic chord).

Q2. Two voices a perfect fifth apart both rise by step to another perfect fifth. Name the error and the rule it breaks. [2 points]

• Cue. Parallel perfect fifths; perfect fifths must not move in the same direction to another perfect fifth, because the voices lose independence.