A harmonic interval is the distance between two pitches that sound simultaneously, labeled by size (second, fifth, etc.) and quality (major, minor, perfect, augmented, or diminished). In AP Music Theory, harmonic intervals are the building blocks of chords and voice leading.
A harmonic interval measures the distance between two notes played at the same time. That's the whole trick of the word "harmonic" here. If the two notes happen one after another, that's a melodic interval; stack them vertically and you've got a harmonic one.
Every harmonic interval gets two labels. Size counts the letter names spanned (a third, a fifth, a seventh), and quality refines it (major, minor, perfect, augmented, or diminished). Per the CED (PIT-1.L.1), some intervals also have unique names like the unison and the tritone, and intervals that sound the same but are spelled differently are enharmonic equivalents. D up to G# (an augmented fourth) sounds identical to D up to Ab (a diminished fifth), but the spelling matters for analysis. Harmonic intervals also carry a consonance/dissonance label in common practice style. Perfect consonances like the perfect fifth and octave are stable, while dissonances like the second, seventh, and tritone create tension that typically resolves.
Harmonic intervals live in Topic 2.5 (Interval Size and Quality) in Unit 2, supporting learning objective 2.5.A, which asks you to describe the size and quality of an interval in both performed music (aural skills) and notated music (score reading). That dual demand is unusual. You have to recognize a minor seventh by ear in a recording and spell one correctly on a staff.
Here's the bigger payoff. Harmonic intervals are the atoms of everything in Units 3 through 6. A triad is just two harmonic thirds stacked up. A 4-3 suspension is a dissonant harmonic fourth above the bass resolving to a consonant third. Parallel fifths, the classic part-writing error, are a harmonic interval problem. If you can't name the interval between two simultaneous notes quickly, the entire harmony half of the course gets harder.
Keep studying AP Music Theory Unit 2
Visual cheatsheet
view galleryMelodic Intervals (Unit 2)
Same measuring system, different orientation. Melodic intervals are horizontal (notes in sequence) and harmonic intervals are vertical (notes together). The size and quality rules are identical, so mastering one gets you both. The exam just tests them in different listening contexts.
Interval Quality (Unit 2)
Quality is the second half of every harmonic interval's name. A "fifth" alone isn't enough on the exam. A perfect fifth is a stable consonance while a diminished fifth is a dissonance that demands resolution, and that difference drives how chords function.
Chord (Unit 3)
A chord is just harmonic intervals stacked together. A major triad is a major third with a minor third on top. When you analyze chord quality in Unit 3, you're really doing rapid-fire harmonic interval identification.
Part-writing (Units 4-6)
Part-writing rules are written in the language of harmonic intervals. Avoiding parallel fifths and octaves, resolving the tritone, and handling a 4-3 suspension all require you to track the harmonic intervals between voices measure by measure.
Harmonic intervals show up in three main ways. First, straight identification, where multiple-choice questions show or play two simultaneous notes and ask for size and quality. Second, consonance and dissonance classification, where questions ask which harmonic interval counts as a perfect consonance (perfect fifth, octave, unison) or which dissonance typically requires resolution in common practice style (seconds, sevenths, the tritone). Third, applied analysis, like identifying the harmonic intervals a suspended note forms against the bass in a 4-3 suspension within a four-part chorale. No released FRQ uses the phrase "harmonic interval" verbatim, but the part-writing and harmonic dictation FRQs are graded partly on the harmonic intervals you create between voices, so you're being tested on this skill even when the term never appears.
Both use the exact same size-and-quality labels, so the names look interchangeable. The difference is timing. Harmonic intervals are two pitches sounding simultaneously (vertical, read up the staff), while melodic intervals are two pitches sounding in succession (horizontal, read left to right). On aural questions this matters a lot, because hearing a major sixth as two blended tones feels very different from hearing it as a leap in a melody.
A harmonic interval is the distance between two pitches sounding at the same time, while a melodic interval is between pitches sounding one after another.
Every harmonic interval is named by size (second, third, fifth, etc.) and quality (major, minor, perfect, augmented, or diminished).
Enharmonic equivalents like the augmented fourth (D to G#) and diminished fifth (D to Ab) sound identical but are spelled and analyzed differently.
Perfect consonances include the unison, perfect fifth, and octave, while seconds, sevenths, and the tritone are dissonances that typically resolve in common practice style.
LO 2.5.A requires you to identify harmonic intervals both by ear in performed music and by sight in notated music.
Harmonic intervals are the building blocks of chords, suspensions, and part-writing rules in Units 3 through 6.
A harmonic interval is the distance between two pitches played simultaneously, labeled by size and quality (like a perfect fifth or minor seventh). It's covered in Topic 2.5 and underpins all chord and voice-leading analysis later in the course.
Harmonic intervals are two notes sounding at the same time (vertical), while melodic intervals are two notes sounding one after another (horizontal). The size and quality labels are identical for both.
It can be, whenever its two pitches sound together. The tritone (an augmented fourth or its enharmonic equivalent, the diminished fifth) is a dissonant harmonic interval that typically resolves in common practice style, which makes it a favorite on AP questions.
They sound identical but they are not the same on paper. D up to G# is an augmented fourth and D up to Ab is a diminished fifth; they're enharmonic equivalents, and AP questions expect you to use the spelling that matches the notation.
In common practice theory, the unison, perfect fifth, and octave are perfect consonances, and thirds and sixths are imperfect consonances. Seconds, sevenths, and the tritone are dissonances that typically require resolution, like the fourth resolving to a third in a 4-3 suspension.
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