In AP Music Theory, dissonant describes intervals or chords that sound unstable and create tension demanding resolution, including 2nds, 7ths, the tritone, and (in two-voice or bass contexts) the perfect 4th. Dissonance drives harmonic motion by resolving to consonance, usually by step.
A dissonant sonority is one that sounds tense, unstable, or "clashy" and pulls toward resolution. In the common-practice style AP Music Theory is built on, dissonance isn't a vibe judgment, it's a category. The dissonant intervals are the major and minor 2nd, the major and minor 7th, and the tritone (augmented 4th / diminished 5th). The perfect 4th counts as dissonant when it occurs against the bass. Everything else (unison, 3rds, perfect 5th, 6ths, octave) is consonant.
Here's the part that matters for your score: dissonance comes with rules. Common-practice dissonance is prepared and resolved, almost always by step. The chordal seventh resolves down by step. The leading tone resolves up to tonic. Nonchord tones like passing tones, suspensions, and neighbor tones are dissonant notes with specific entry-and-exit patterns. Think of dissonance as a debt the music takes on. It creates tension, and the style demands the music pay it back by resolving to consonance.
Consonance and dissonance show up at every level of the course. In Unit 1 you classify intervals as consonant or dissonant, which is foundational vocabulary. In Units 4 and 5 (Harmony and Voice Leading), dissonance treatment becomes a graded skill, since the chordal seventh of a V7 must resolve down by step and the leading tone must resolve up, and part-writing FRQs penalize you when they don't. In Unit 6, embellishing tones (nonchord tones) are literally a taxonomy of how dissonance enters and leaves a texture. If you can't identify which note is dissonant against the chord, you can't label a suspension versus an appoggiatura versus a passing tone. Dissonance is also the engine of harmonic function: dominant chords sound like they "need to go somewhere" largely because of the dissonant tritone inside V7.
Keep studying AP Music Theory Unit 6
Visual cheatsheet
view galleryConsonant (Unit 1)
Consonant is the flip side of dissonant, and the two only mean anything as a pair. Stable consonances are where dissonances resolve. Memorize the interval lists for both, because MCQs test the classification directly.
Chordal Seventh Resolution (Units 4-5)
The seventh of a chord is a built-in dissonance, so it follows the dissonance rulebook. It resolves down by step. This is one of the most commonly checked voice-leading rules on the part-writing FRQs.
Nonchord Tones (Unit 6)
Nonchord tones are dissonances with job descriptions. A passing tone enters and leaves by step, a suspension is prepared then resolves down, an escape tone steps in and leaps out. Identifying them starts with spotting which note clashes with the chord.
Leading Tone (Units 2-4)
The leading tone forms a dissonant tritone with scale degree 4 inside V7, which is why dominant chords feel so pulled toward tonic. Its required resolution up to scale degree 1 is the melodic version of dissonance resolving to consonance.
Dissonance gets tested three ways. First, interval-classification MCQs ask you to sort intervals into consonant and dissonant, including the tricky perfect 4th. Second, aural and score-based questions on embellishing tones make you identify how a dissonant note resolves. Fiveable practice questions, for example, ask how an escape tone differs from a neighbor tone in its movement and resolution, and the answer hinges on how each one exits the dissonance (step versus leap). Third, the part-writing and figured bass FRQs grade your dissonance treatment directly. Leave a chordal seventh hanging or resolve it upward, and you lose points even if the chords are correct.
Consonant intervals (3rds, 6ths, perfect 5ths, octaves, unisons) sound stable and don't need to go anywhere. Dissonant intervals (2nds, 7ths, the tritone) sound unstable and demand stepwise resolution. The classic trap is the perfect 4th, which is consonant in the abstract but treated as dissonant when it sounds against the bass. Don't confuse dissonant with "sounds bad," either. Dissonance is what makes harmony move.
Dissonant intervals are the major and minor 2nd, major and minor 7th, and the tritone, plus the perfect 4th when it occurs against the bass.
In common-practice style, dissonance must resolve, almost always by step, into a consonance.
The chordal seventh is a dissonance that resolves down by step, and the leading tone resolves up to tonic; both are graded on part-writing FRQs.
Nonchord tones (passing tones, neighbor tones, suspensions, escape tones, etc.) are classified by how the dissonant note enters and resolves.
Dissonance is functional, not just expressive. The tritone inside V7 is a big reason dominant harmony pulls so strongly toward tonic.
Dissonant describes an interval or chord that sounds unstable and creates tension that pulls toward resolution. On the exam, the dissonant intervals are 2nds, 7ths, the tritone, and the perfect 4th when it sounds against the bass.
It depends on context, which is exactly why the exam loves it. In common-practice voice leading, a perfect 4th above the bass is treated as a dissonance that needs resolution, while a 4th between upper voices is generally fine.
No. Dissonance is a technical category, not a quality judgment. Dissonant intervals create the tension that makes progressions feel like they're going somewhere, and a V7 chord without its dissonant tritone would lose most of its pull toward tonic.
A nonchord tone is one specific kind of dissonance, a note that doesn't belong to the current chord. But dissonance can also live inside a chord, like the seventh of V7 or the tritone between the leading tone and scale degree 4. All nonchord tones are dissonant against the chord, but not all dissonances are nonchord tones.
By step, into a consonance. The chordal seventh resolves down by step, the leading tone resolves up to tonic, and suspensions resolve down. Breaking these resolution rules costs points on the harmonization and figured bass FRQs.