When we listen to music, it is the chords that make up a harmony. Chords are defined by having at least 3 pitches and are played (or sung) at the same time. Chords can also be implied if pitches are played in a group, such as an arpeggio.
Here is an example of a chord played simultaneously:
Here is an example of an arpeggio, which outlines the tones of a chord.
Chords and harmonies are important because they add depth to the music, and they give the music a sense of motion, tension, and resolution. In the tradition of Western music, there are two basic types of chords:
In the tradition of Western music, there are two basic types of chords:
- Triads: chords that consist of 3 distinct pitches, a combination of two thirds (intervals) stacked on one another [](Unit%203%20Music%20Fundamentals%20III%20(Triads%20and%20Seventh%20%2094a1b419277849f2bd00a223eaeb4a3d/Screen_Shot_2020-08-18_at_7.43.55_PM.png)
- Seventh chords: chords that consist of 4 distinct pitches, a combination of three thirds (intervals) stacked on one another.
Triads
In music theory, a triad is considered a basic building block of tonal harmony, and it is the most common type of chord found in Western classical music and other styles of music. The word "triad" comes from the Latin word "tres," meaning "three," and triads are usually built by stacking thirds on top of each other.
There are four types of triads: major (M), minor (m), diminished (d), and augmented (A). A major triad consists of a root note, a major third interval above the root, and a perfect fifth interval above the root. A minor triad consists of a root note, a minor third interval above the root, and a perfect fifth interval above the root. A diminished triad consists of a root note, a minor third interval above the root, and a diminished fifth interval above the root. An augmented triad consists of a root note, a major third interval above the root, and an augmented fifth interval above the root.
Triads are typically played with the root note in the bass, or lowest part, and the other two notes stacked on top. However, they can also be played in inversions, where the root note is not in the bass. In a first inversion triad, the middle note is played in the bass, and in a second inversion triad, the top note is played in the bass. Inverting a triad can change the overall sound and feel of the chord, and we will usually invert chords so we can have good voice leading in our music.
From right to left: C Major, C minor, C diminished, C augmented
All the above chords, no matter their quality, consider this to be in the root position when the tonic of a chord is at the bottom of the triad. The tonic here is C.
Looking Ahead: Seventh Chords
Seventh chords are chords that consist of four notes, with the fourth note being a seventh interval above the root note. Like triads, seventh chords are an important part of tonal harmony and are found in many different styles of music. There are several types of seventh chords, including major seventh chords, minor seventh chords, dominant seventh chords, diminished seventh chords, and half-diminished seventh chords.
A major seventh chord consists of a root note, a major third interval above the root, a perfect fifth interval above the root, and a major seventh interval above the root. It has a bright, happy sound and is often used to create a sense of resolution or closure in a piece of music. We might also write major seventh chords as MM chords, since there is a major triad followed by a major third.
A minor seventh chord (mm) consists of a root note, a minor third interval above the root, a perfect fifth interval above the root, and a minor seventh interval above the root. It has a more mellow, contemplative sound and is often used to create a sense of tension or dissonance.
A dominant seventh chord (Mm) consists of a root note, a major third interval above the root, a perfect fifth interval above the root, and a minor seventh interval above the root. It is one of the most common types of seventh chords and is used extensively in blues, jazz, and rock music. It has a strong, bluesy sound and is often used to create a sense of tension or instability that needs to be resolved.
A diminished seventh chord consists of a root note, a minor third interval above the root, a diminished fifth interval above the root, and a diminished seventh interval above the root. It has a very tense, dissonant sound and is used to create a sense of instability or unease.
The half-diminished seventh chord is similar to a diminished seventh chord, but with a minor seventh interval instead of a diminished seventh interval. Sometimes, we will denote seventh chords with a little circle and a line through it. It has a very tense, dissonant sound and is often used to create a sense of instability or unease in a piece of music.
The half-diminished seventh chord is often used as a substitute for a dominant seventh chord in jazz, and it is an important part of the harmonic language of the genre. It can also be found in classical music, where it is sometimes used to create a sense of tension or dissonance that needs to be resolved. In rock and pop music, the half-diminished seventh chord is not as common, but it can be used to add variety and interest to chord progressions and melodies.
Seventh chords are typically played with the root note in the bass, or lowest part, and the other three notes stacked on top. Like triads, they can also be played in inversions, where the root note is not in the bass. In a first inversion seventh chord, the middle note (the third) is played in the bass, and in a second inversion seventh chord, the fifth is played in the bass. There is also a third inversion, where the seventh is played in the base, but this inversion is not used very frequently.
Here are examples of the different types of seventh chords
Image via Music Theory Teacher
🦜Polly wants a progress tracker: How do you spell a Bb major chord? How do you spell a 7th chord in E minor?
Identifying Triads and Seventh Chords by Ear
On the AP Music Theory Exam, you will have to identify the type, quality, and inversion of a chord by ear, given a specific chord progression. There are several strategies that you can use to help you identify triads and seventh chords by ear.
One strategy is to listen for the intervals between the notes in the chord. Triads and seventh chords will both consist of four notes, but in triads, one note will be doubled. Listening for intervals is a little dangerous because the chords might be inverted, but if you are sure about one note and you can get a second note using this method, you will be able to identify the chord much more easily.
Another strategy is to listen for the overall sound and feel of the chord. Different types of triads and seventh chords have distinctive sounds that can help you identify them. For example, major triads have a bright, happy sound, minor triads have a more mellow, contemplative sound, and diminished triads have a tense, dissonant sound.
Similarly, dominant seventh chords have a strong, bluesy sound, minor seventh chords have a more mellow, relaxed sound, and half-diminished seventh chords have a very tense, dissonant sound. By listening for these characteristics, you can get a sense of the type of triad or seventh chord that you are hearing.
You can also use your knowledge of chord progressions and common harmonic patterns to help you identify triads and seventh chords by ear. Many songs follow predictable chord progressions, and if you know what to listen for, you can often predict what chord will come next based on the chords that have come before.
For example, you might expect to hear a V-I cadence at the end of the chord progression. If you look at past AP exams, there are many such patterns that they like to reuse. By listening for these patterns, you can get a better sense of the overall structure of the music and make more accurate identifications of the chords that you are hearing.
Finally, you can use your knowledge of scales to help you identify triads and seventh chords by ear. Different scales and modes have distinctive patterns of whole and half steps that can help you identify the root notes of chords and the intervals between them.
For example, if you know that a piece of music is in the key of C major, and you hear a chord with a root note of G, a major third interval above the root, and a perfect fifth interval above the root, you can infer that the chord is a G major triad, since these intervals match the intervals in the G major scale. Often, listening for the root note will help you identify the chord, because there are only a few possibilities given other context clues.
I used the website Teoria to practice identifying chord progressions. You can start with only a few chords, and add more complex ones as you move on.
Frequently Asked Questions
What's the difference between a major and minor triad and how do I hear it?
A major triad = root + major third + perfect fifth (stacked thirds: M3 then m3). A minor triad = root + minor third + perfect fifth (m3 then M3). That interval pattern (the third) is what gives each triad its quality (PIT-1.O, PIT-1.O.2–3). To hear the difference: sing or play the root, then the third. If that third sounds “brighter” or “open,” it’s a major third → major triad; if it sounds “darker” or “sadder,” it’s a minor third → minor triad. Try arpeggiating the triad (root–third–fifth) and compare. Another trick: sing the major scale’s root and the third scale degree—that third equals the major triad’s third; the lowered third (minor third) gives the minor triad its color. On the AP exam you’ll be asked to identify chord quality in both aural and notated contexts (Section I.A and PIT-1.O). For extra practice, review Topic 3.1 (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc), the Unit 3 overview (https://library.fiveable.me/music-theory/unit-3), and try problems (https://library.fiveable.me/practice/music-theory).
How do I identify chord qualities when I'm listening to a song?
Start by thinking like the CED: a triad is root–3rd–5th (stacked thirds). When you listen, try these quick steps: 1. Find the root (lowest sustained or resolving note)—that gives you the chord name. (CED: PIT-1.O.2) 2. Hear the 3rd above the root: if it’s a major 3rd (4 semitones) the chord is major (M); if it’s a minor 3rd (3 semitones) it’s minor (m). (CED: PIT-1.O.3) 3. Check the 5th: perfect = major/minor triad, diminished (d) = flatted 5 (diminished 5th), augmented (A) = raised 5 (augmented 5th). 4. If notes are arpeggiated, mentally stack them as thirds to test the intervals (triads can be in any inversion). (CED: PIT-1.O.1) Aural practice matters—the AP aural section tests performed-music analysis (Section I, Part A). For targeted listening practice and examples, use the Topic 3.1 study guide (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc) and 1000+ practice items (https://library.fiveable.me/practice/music-theory).
I'm confused about stacking thirds - can someone explain this in simple terms?
Think of stacking thirds as building a chord by skipping every other scale step: start on a note (the root), go up a third, then up another third. Those three notes—root, third, fifth—form a triad when stacked in thirds (CED PIT-1.O.1–2). The size of those two thirds determines the triad quality: - Major triad = major third + minor third (bright) - Minor triad = minor third + major third (darker) - Diminished triad = minor third + minor third (tense) - Augmented triad = major third + major third (unstable) In root position the root is on the bottom; inversions just reorder the same stacked-thirds notes (CED keywords: root position, first/second inversion). On the AP, you’ll need to recognize these by ear and in notation (PIT-1.O), so practice identifying the interval pattern and naming root/third/fifth. For a focused review, see the Topic 3.1 study guide (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc) and try practice problems (https://library.fiveable.me/practice/music-theory).
What does it mean when a chord is diminished vs augmented?
A diminished triad is built by stacking two minor thirds: root → minor 3rd → another minor 3rd. That gives a root-to-fifth interval of a diminished fifth (tritone). Notated symbols: ° or d. It sounds tense/unstable and commonly functions as a leading, unstable sonority. An augmented triad is built by stacking two major thirds: root → major 3rd → another major 3rd, producing an augmented fifth between root and fifth. Notated symbols: + or A. It sounds bright, ambiguous, and non-diatonic (it doesn’t belong to a single major/minor key without alteration). On the AP exam you should be able to identify these by spelling (stacked thirds) and by the specific third sizes (PIT-1.O.1–3). For a quick refresh, see the Topic 3.1 study guide (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc), the Unit 3 overview (https://library.fiveable.me/music-theory/unit-3), and practice questions (https://library.fiveable.me/practice/music-theory).
How do I write the symbols for major, minor, diminished and augmented chords correctly?
Write the chord-quality symbol next to the chord’s root (or its Roman numeral) using these standard notations from the CED: - Major: M or nothing in lead-sheet form—e.g., C or C Major (Roman numeral: I). CED uses “M.” - Minor: m—e.g., Cm (Roman numeral: i). - Diminished: d or °—e.g., C° or Cd (Roman numeral: vii° for a diatonic diminished triad). The circle (°) is common in analysis. - Augmented: A or +—e.g., C+ or CA (Roman numeral: I+ or III+ when tonicized). AP tip: on the exam you may need to label triads in notated music (use Roman numerals with case and °/+ where appropriate) or describe what you hear (use M, m, d/°, A/+). The course study guide for Topic 3.1 shows examples and practice (see: https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc). For extra practice, try problems at https://library.fiveable.me/practice/music-theory.
Can someone help me understand what makes a chord sound happy or sad?
A chord sounds “happy” or “sad” mostly because of its triad quality—the intervals inside the chord. A major triad (root + major 3rd + perfect 5th) has a brighter, more “happy” sound; a minor triad (root + minor 3rd + perfect 5th) sounds darker or “sad.” Diminished (minor 3rd + minor 3rd = diminished 5th) and augmented (major 3rd + major 3rd = raised 5th) triads sound tense or unstable. Those qualities come straight from the stacked thirds that define triads (CED PIT-1.O.1–3). Context matters too: melody, voicing, inversions, doubling, dynamics, and tempo change how you perceive emotion. On the AP exam you’ll need to identify these qualities both by ear and in notation (Section I aural and non-aural tasks), so practice recognizing major vs. minor thirds and unstable intervals. For a quick review, see the Topic 3.1 study guide (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc) and try practice problems (https://library.fiveable.me/practice/music-theory).
I don't get how to identify the root, third, and fifth in a chord - help?
Start by picturing the chord as stacked thirds (that’s the “essence” the CED mentions). If the chord is written in root position (notes stacked like C–E–G), the bottom note is the root, the note a third above it is the third, and the note a fifth above the root is the fifth. Quality comes from those interval sizes: major triad = M3 + m3 (root→third = major 3rd), minor = m3 + M3, diminished = m3 + m3, augmented = M3 + M3 (CED PIT-1.O.2–.3). If the chord’s inverted, find the arrangement of chord tones: in first inversion the third is in the bass, in second inversion the fifth is in the bass. To ID the root from an inversion, re-stack the chord in your head in thirds (or count intervals up from each note until you find a 3rd+3rd or 3rd+major/minor 3rd pattern that matches a triad). For practice, review Topic 3.1 (study guide: https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc) and drill problems at https://library.fiveable.me/practice/music-theory—this is exactly what AP questions test.
What's the easiest way to remember the difference between all four triad qualities?
Quick trick: identify the third first, then the fifth. - Third = major (M3, 4 semitones) or minor (m3, 3 semitones). That immediately tells you major vs. minor triad (M = M3 + P5; m = m3 + P5). - If the third is minor and the fifth is one semitone smaller than a perfect fifth (6 semitones above the root), it’s diminished (m3 + d5). - If the third is major and the fifth is one semitone larger than perfect (8 semitones above the root), it’s augmented (M3 + A5). Hear it: major = “bright/stable,” minor = “darker/stable,” diminished = “tense/unstable,” augmented = “open/ambiguous.” For AP exam items (PIT-1.O.1–3) you’ll be asked to describe these by ear or by spelling in notation—practice naming the third and fifth quickly. Review this topic on Fiveable’s study guide (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc) and drill with practice questions (https://library.fiveable.me/practice/music-theory).
How do I analyze chord qualities in my music theory portfolio pieces?
Start by treating every chord as a stacked-third: find the root, then the 3rd and 5th (if it’s arpeggiated, group the sounding pitches as a chord). Measure the intervals above the root: - Major triad = root–M3 + m3 (M) - Minor triad = root–m3 + M3 (m) - Diminished triad = root–m3 + m3 (d or °) - Augmented triad = root–M3 + M3 (A or +) Quality doesn’t change with inversion—label the chord quality (M, m, d, A) and then its inversion (root, 6, 6/4). In performed music, confirm by ear: arpeggios or simultaneous tones show the same interval structure (CED PIT-1.O.1–3). For your portfolio, annotate the score: write root, interval sizes, chord quality symbol, and inversion. That shows you can “describe the quality of a chord in performed and notated music” as required on the AP (PIT-1.O). Review Topic 3.1 on Fiveable for examples (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc) and practice more at (https://library.fiveable.me/practice/music-theory).
Why do some chords sound stable and others sound like they need to resolve?
Some chords sound “stable” and others “need to resolve” because of their interval structure and the tension that creates. Triads are built of stacked thirds: major (M) and minor (m) triads contain intervals (a major or minor third + a perfect fifth) that sound consonant and therefore stable. Diminished (d) triads have a minor third + a diminished fifth (a tritone-ish sound) and augmented (A) triads have enlarged intervals; those altered fifths produce more dissonance and a sense of instability. Also, certain tones like the leading tone (the raised 7th in major/minor) are “tendency tones” that want to resolve by step to the tonic. In short: chord quality (M, m, d, A) + specific intervals (especially the fifth/third and leading tones) determine how much a chord feels like it must move. For AP focus, be able to identify triad quality by spelling and explain why a chord functions as stable or unstable (CED PIT-1.O; see Topic 3.1 study guide for review) (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc). Practice identifying and hearing these on Fiveable’s Unit 3 page (https://library.fiveable.me/music-theory/unit-3) and with extra exercises (https://library.fiveable.me/practice/music-theory).
What instruments should I use to demonstrate different chord qualities in my performance?
Use a piano or guitar as your primary demonstrator—both clearly show triad spacing (root, third, fifth), inversions, and arpeggiation so students can hear major, minor, diminished, and augmented qualities. Piano is best for AP-style aural practice (Section I, Part A and harmonic dictation) because it gives steady sustain and exact voicings; guitar is great for pop/folk contexts and visible chord shapes. Add a sustained string or brass (violin, cello, trombone) to highlight how timbre affects perception of quality, and use voice or choir to show how doubling and register change color. For clarity on augmented/diminished sonorities, use a marimba or piano with single-note arpeggios so intervals aren’t blurred. Demonstrate inversions and figured bass examples on piano to mirror exam tasks (root position, 6, 6/5, etc.). For lesson plans and more examples tied to the CED, see the Topic 3.1 study guide (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc), the Unit 3 overview (https://library.fiveable.me/music-theory/unit-3), and tons of practice problems (https://library.fiveable.me/practice/music-theory).
How do I show that I understand chord qualities in both written and performed music for AP?
Show it two ways: on the page and by ear. On paper: spell the chord in stacked thirds, name the chord tones (root, third, fifth), give its root position or inversion, and label the quality M, m, d, or A. Use interval structure to decide quality: major triad = M3 + m3 (P5), minor = m3 + M3 (P5), diminished = m3 + m3 (d5), augmented = M3 + M3 (A5). Write Roman numerals when diatonic context applies. By ear / performed music: arpeggiate or hum the chord, find the third and fifth above the root, and judge whether the third is major or minor (that tells M vs m); check whether the fifth is diminished or augmented for d/A. AP tasks test both aural and notated skills (Section I Part A aural, Part B non-aural, and harmonic dictation/free response—CED PIT-1.O). Practice both skills with the Topic 3.1 study guide (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc) and hundreds of practice problems (https://library.fiveable.me/practice/music-theory).
I keep mixing up diminished and minor chords - what's the trick to telling them apart?
Quick trick: stack the triad in thirds and check the intervals. A minor triad = root → minor third (3 semitones) → major third (4 semitones)—that gives a perfect fifth between root and fifth. A diminished triad = root → minor third → another minor third (3 + 3)—that makes a diminished fifth (tritone) between root and fifth. So either: - Look at root→third: if it’s a minor 3rd, next is either major (minor triad) or minor (diminished triad). - Or check root→fifth: perfect 5th = minor triad; diminished 5th (6 semitones) = diminished triad. On the AP, you’ll identify quality from spelled notes (stacked thirds) in any inversion—so find the chord tones and reconstruct the thirds. For more practice, see the Topic 3.1 study guide (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc), the Unit 3 overview (https://library.fiveable.me/music-theory/unit-3), and 1000+ practice problems (https://library.fiveable.me/practice/music-theory).
Can you explain arpeggiation and how it relates to chord identification?
Arpeggiation = sounding a chord’s tones successively (an arpeggio) instead of all at once. The CED explicitly says chords can be perceived through arpeggiation, so when you hear an arpeggio you're still hearing a triad or seventh chord (stacked thirds), just spread out. To ID the chord quality from an arpeggio: listen or look for the three essential chord members (root, third, fifth). Determine the intervals above the root (major third = M, minor third = m, two minor thirds = diminished, augmented second + major third = augmented). Be careful: inversions and voicings can hide the root—if the lowest-sounding pitch isn’t the root, reconstruct the stacked-thirds order (or find the third and fifth and infer the root). On the AP exam this shows up in aural questions and harmonic dictation, so practice recognizing arpeggiated triads by quality and inversion. Review Topic 3.1 (study guide) and drill with practice problems (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc) and (https://library.fiveable.me/practice/music-theory).
What's the best way to practice hearing the difference between major and augmented triads?
Practice the sound difference by isolating the interval that changes: the fifth. A major triad = root + major third + perfect fifth; an augmented triad = root + major third + augmented (raised) fifth (two major thirds stacked). Try this routine (10–20 min/day): - Play and sing: sing the root, then the third, then the fifth. Do that for a major triad, then raise the fifth and sing the augmented triad—notice the “wider” step from third to fifth. - Arpeggio drill: hear root-position, 1st, and 2nd inversion arpeggios. Augmented sounds more open/unstable because both intervals are major thirds. - A/B comparisons: listen to short clips of major vs. augmented triads back-to-back and label them; start in one key and transpose. - Transcription: include these in harmonic dictation practice (this maps to AP aural skills, Section I Part A and harmonic dictation free-response). For guided exercises and more examples, see the Topic 3.1 study guide (https://library.fiveable.me/music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc) and hit the 1000+ practice problems (https://library.fiveable.me/practice/music-theory).