Writing passing tones and neighbor tones means adding short, unaccented eighth-note motion to a bass line so it connects smoothly with a given soprano line. In AP Music Theory, you do this in 18th-century chorale style by filling in steps between chord tones (passing tones) or stepping away from and back to a chord tone (neighbor tones), while keeping correct voice leading. The cleanest spots to add them are against a stationary soprano, in parallel thirds or sixths with the soprano, or during a voice exchange.

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Why This Matters for the AP Music Theory Exam

This skill shows up when you compose, not just analyze. You add embellishments like passing and neighbor tones only when they are signaled to you, such as by figured bass or by Roman and Arabic numerals, and you stick to unaccented passing and neighbor tones when you are composing freely. That means knowing exactly where an unaccented eighth-note tone is allowed, and how it interacts with the soprano line, helps you write a clean bass line without breaking 18th-century voice-leading rules.

Building fluency here also supports the analysis side of the course. The better you understand how composers fill in steps and decorate held notes, the faster you can spot these tones in performed and notated music during the multiple-choice section.

Key Takeaways

A passing tone fills the step between two chord tones a third apart; a neighbor tone steps away from a chord tone and returns to it.
When composing, use unaccented passing and neighbor tones, placed on weak beats (usually as eighth notes between quarter-note chord tones).
Embellishing tones must be approached and left by step. If the motion leaps, it is not a passing or neighbor tone.
A common pattern is two bass eighth notes against one quarter note in a stationary soprano.
Good places to add bass embellishments: a stationary soprano, parallel thirds or sixths with the soprano, or a voice exchange between soprano and bass.
Watch out for parallel fifths and octaves when you add the extra notes; the embellishment should not create forbidden parallels.

Review of Passing Tones and Neighbor Tones

Passing Tones

A passing tone is a nonharmonic tone that moves stepwise between two chord tones, filling in the gap when those chord tones are a third apart. It adds motion and keeps a line moving smoothly instead of leaping.

Consider moving from a I chord to a iii chord. In the bass line you would have the tonic followed by the mediant. You can add a supertonic passing tone between them so the bass moves stepwise: tonic to supertonic to mediant. In Ab Major, that gives an Ab-Bb-C line in the bass.

When composing for the exam, you write unaccented passing tones, meaning the passing tone lands on a weaker beat than the chord tones around it. The chord tone falls on the strong beat (the harmonic beat), and the passing tone fits in on the weak part, usually as an eighth note. If chords move in quarter notes, a passing tone fits on the off-eighth.

Passing tones can be diatonic (inside the key's scale) or chromatic (outside it). A chromatic passing tone might turn a C-to-D step into C-C#-D, or fill a leap with a chromatic line. For AP composition tasks, stick with diatonic, unaccented passing tones.

Neighbor Tones

A neighbor tone is a nonharmonic tone that steps away from a chord tone and then returns to the same pitch. It works when a note is held or repeated across two chords. If a C is sustained in a voice, you can step down to B and back, giving a C-B-C figure.

There are two kinds. An upper neighbor steps up and returns; a lower neighbor steps down and returns. Like passing tones, neighbor tones can be diatonic or chromatic, but the motion away and back must be by step. A figure like C-E-C is not a neighbor tone, because E is a leap away from C (that pattern is an escape tone, covered in 6.3).

Writing Passing and Neighbor Tones

For this skill in AP Music Theory, you compose a bass line under a given soprano line and bring it to life with unaccented passing and/or neighbor tones. The basic frame is quarter notes; you enliven it with eighth-note motion in the right spots.

There are three reliable situations where a bass embellishment works well with the soprano:

1. Complement a stationary soprano. When the soprano holds a quarter note, you can put two bass eighth notes against it. The first is a chord tone, the second is an unaccented passing or neighbor tone, then you land on the next chord tone. This keeps the strong beats clean and adds motion only in the bass.

2. Move in parallel thirds or sixths with the soprano. If the soprano line moves stepwise, a bass line running a third or a sixth below in parallel can use passing-tone motion to stay smooth and consonant with it.

3. Engage in voice exchange with the soprano. In a voice exchange, the bass and soprano trade pitches. For example, the bass moves up G-A-B (with A as a passing tone) while the soprano moves down from B to G. Adding the passing tone in the bass during the exchange creates a smooth, satisfying line.

In every case, the embellishing tone must be approached and left by step, and it should fall on a weak beat. As you add the extra eighth notes, double-check that you have not created parallel fifths or octaves or other voice-leading problems between the bass and the upper voices. The embellishment should improve the line, not break the counterpoint.

How to Use This on the AP Music Theory Exam

Free Response

Add passing and neighbor tones only when they fit and only as unaccented tones when you are composing a bass line. Keep chord tones on the strong beats.
Use the three safe formations: stationary soprano with two bass eighths, parallel thirds or sixths, or a voice exchange.
After writing each embellishment, scan vertically for parallel fifths and octaves with the soprano and inner voices.
Make sure every passing tone fills a third between chord tones and every neighbor tone returns to the same pitch, both by step.

MCQ

Be ready to recognize these tones in notated and performed music. Ask whether the note is approached and left by step, and whether it fills a gap (passing) or returns to its start (neighbor).
Check rhythmic placement to label a tone accented or unaccented.

Common Trap

Counting rhythm wrong when you insert tones. If chords move in half notes, do not jam in three equal quarter notes. Keep the chord tone on the beat and fit the embellishments into the weak subdivisions.

Common Misconceptions

"Passing and neighbor tones can leap." They cannot. Both must move by step. A leap away and back is an escape tone or another figure, not a neighbor tone.
"Embellishments go on the strong beat." When you compose, you use unaccented tones on weak beats. The chord tone stays on the strong (harmonic) beat.
"A neighbor tone connects two different chord tones." No. A neighbor tone leaves a pitch and returns to the same pitch. A passing tone is the one that connects two different chord tones a third apart.
"Adding tones can never cause errors." Inserting eighth notes can create parallel fifths or octaves with another voice. Always check your voice leading after embellishing.
"Embellishments belong only in the soprano." For this composing task you add them to the bass line under a given soprano, using stationary-soprano, parallel third/sixth, or voice-exchange situations.

Vocabulary

The following words are mentioned explicitly in the College Board Course and Exam Description for this topic.

Term	Definition
18th-century harmony	The harmonic practices and conventions of common-practice period music from the 1700s, including rules for chord construction and voice leading.
4-3 suspension	A suspension where a fourth above the bass is held and resolves to a third, commonly notated in figured bass as 4-3.
accented nonharmonic tone	A nonharmonic tone that falls directly on a beat, making it rhythmically prominent.
anticipation	A nonharmonic tone that sounds before the chord it belongs to, typically resolving by step to a chord tone.
appoggiatura	A nonharmonic tone that is approached by leap and resolved by step to a chord tone, typically creating emphasis or dissonance.
bass line	The lowest melodic line in a musical composition that often implies harmonic progressions through its note choices.
chain of suspensions	A series of successive suspensions that occur in sequence, creating a continuous pattern of suspended and resolving tones.
chorale style	A compositional style featuring four-part harmony with block chords, typically used in 18th-century German hymn settings.
embellishing tones	Pitches that do not belong to the underlying harmonic chord and serve to embellish or decorate the melody.
embellishment	A decorative musical element used to enhance or ornament a melodic line.
escape tone	A nonharmonic tone that is approached by step and left by leap, creating a sense of escape from the expected resolution.
figured bass	A notational system using Arabic numerals below a bass note to indicate the intervals and pitches of the chord to be played above that bass note.
lower neighbor	A type of neighbor tone that approaches and resolves from a pitch below the main melodic note.
neighbor tone	A type of nonharmonic tone that includes lower neighbor and upper neighbor classifications based on melodic approach and resolution.
neighbor tones	Embellishing tones that move by step away from and then back to the same harmonic tone.
ornament	A decorative musical figure or embellishing tone used to enhance a melodic line.
parallel sixths	Two melodic lines moving in the same direction with a consistent interval of a sixth between them.
parallel thirds	Two melodic lines moving in the same direction with a consistent interval of a third between them.
passing tone	A type of nonharmonic tone that is melodically approached and resolved in a specific manner, classified as either accented or unaccented based on its rhythmic placement.
pedal point	A sustained or repeated pitch in the bass that remains constant while harmonies change above it, creating a nonharmonic relationship.
preparation	The approach or introduction of a nonharmonic tone, establishing how it enters the melodic line.
rearticulated suspension	A suspension in which the suspended tone is restruck or rearticulated rather than held continuously from the previous chord.
resolution	The movement of a chord tone, typically by step, to another chord tone, often from a dissonant interval to a consonant one.
retardation	A nonharmonic tone that delays the resolution of a chord tone by resolving upward by step to a chord tone, the opposite of a suspension.
Roman numeral progression	A harmonic progression notated using Roman numerals to indicate chord function and quality.
soprano line	The highest melodic line in a musical composition, typically sung by the highest voices or played by the highest instruments.
suspension	A nonharmonic tone created when a note from a previous chord is held or rearticulated over a new chord before resolving downward by step to a chord tone.
trill	An ornament consisting of the rapid alternation between a note and the note above or below it.
unaccented nonharmonic tone	A nonharmonic tone that falls on a division between beats rather than directly on a beat.
unaccented passing tones	Embellishing tones that occur on weak beats and connect two harmonic tones by stepwise motion.
upper neighbor	A type of neighbor tone that approaches and resolves from a pitch above the main melodic note.
voice exchange	A technique where two voices exchange their melodic material or swap positions in the harmonic texture.
voice leading	The technique of moving individual melodic lines (voices) in a musical composition, including considerations for smooth transitions and proper resolution of chords.

Frequently Asked Questions

What is a passing tone in music theory?

A passing tone is a nonharmonic tone that moves by step between two chord tones, usually filling the space between notes a third apart.

What is a neighbor tone?

A neighbor tone steps away from a chord tone and then returns to the same pitch. It can be an upper neighbor or a lower neighbor depending on the direction of the step.

How do you write passing tones on the AP Music Theory exam?

Use unaccented passing tones on weak subdivisions, usually as eighth-note motion between chord tones. The passing tone should be approached and left by step.

How do you write neighbor tones in a bass line?

Start on a chord tone, step up or down to the neighbor tone on a weak subdivision, and return to the original chord tone. Keep the motion stepwise and check the surrounding voices.

What is the difference between passing tones and neighbor tones?

A passing tone connects two different chord tones by step. A neighbor tone leaves a chord tone by step and returns to that same chord tone.

Where should embellishing tones go in AP chorale-style writing?

They work best against a stationary soprano, in parallel thirds or sixths with the soprano, or during a voice exchange. They should not create parallel fifths or octaves.