Getting Started
Having mastered the identification of intervals, we now move to the next level of harmonic complexity: chords. A chord is a foundational unit of harmony, created when three or more notes sound at the same time. Understanding a chord's internal structure, known as its quality, is the essential first step toward analyzing its function and emotional character within a piece of music.
What You Should Be Able to Do
Identify the quality of a triad (major, minor, diminished, or augmented) from notated music.
Aurally distinguish between the four basic triad qualities in performed music.
Accurately spell any of the four triad qualities when given a root note.
Describe the specific interval structure that defines each triad quality.
Differentiate between a triad and a seventh chord.
Key Concepts & Analysis
The concept of chord quality is a prerequisite for understanding functional harmony. Before a chord can be assigned a function like tonic or dominant, its fundamental character, or quality, must be identified. This quality is determined entirely by the specific intervals that make up the chord.
The Building Blocks of Harmony: Triads
A chord is a harmonic structure consisting of three or more pitches sounding simultaneously. The most fundamental type of chord in Western music is the triad, a three-note chord built from a specific pattern of stacked thirds. While other chords exist, such as seventh chords (four-note chords), a mastery of triads is essential.
The unique sound of a triad is its chord quality. This quality is not subjective; it is a direct result of the precise distance between the chord members. We analyze these distances by measuring the intervals from the lowest note, called the root, to the upper notes. There are four primary triad qualities.
Major Triad (M)
The major triad is built with a Major 3rd and a Perfect 5th above the root. Aurally, it is often described as sounding bright, stable, or happy.
Interval Structure: Root, Major 3rd, Perfect 5th.
Stacked Thirds: A Major 3rd on the bottom, with a minor 3rd stacked on top. (e.g., C–E is a M3; E–G is a m3).
Minor Triad (m)
The minor triad is built with a minor 3rd and a Perfect 5th above the root. It shares the stability of the major triad but is often described as sounding dark, somber, or serious.
Interval Structure: Root, minor 3rd, Perfect 5th.
Stacked Thirds: A minor 3rd on the bottom, with a Major 3rd stacked on top. (e.g., C–E♭ is a m3; E♭–G is a M3).
Diminished Triad (° or d)
The diminished triad is built with a minor 3rd and a diminished 5th above the root. This combination of intervals creates a dissonant, unstable sound that often feels like it needs to resolve to another chord.
Interval Structure: Root, minor 3rd, diminished 5th.
Stacked Thirds: A minor 3rd on the bottom, with another minor 3rd stacked on top. (e.g., C–E♭ is a m3; E♭–G♭ is a m3).
Augmented Triad (+ or A)
The augmented triad is built with a Major 3rd and an augmented 5th above the root. Like the diminished triad, it sounds unstable and dissonant, often creating a sense of suspense or surprise.
Interval Structure: Root, Major 3rd, augmented 5th.
Stacked Thirds: A Major 3rd on the bottom, with another Major 3rd stacked on top. (e.g., C–E is a M3; E–G♯ is a M3).
Data & Organization Tools
This table summarizes the construction of the four essential triad qualities. Use it as a quick reference for spelling and identifying chords.
| Quality Name | Abbreviation | Intervals Above Root | Stacked Thirds Formula |
|---|---|---|---|
| Major | M | Major 3rd, Perfect 5th | Major 3rd + minor 3rd |
| Minor | m | minor 3rd, Perfect 5th | minor 3rd + Major 3rd |
| Diminished | ° or d | minor 3rd, diminished 5th | minor 3rd + minor 3rd |
| Augmented | + or A | Major 3rd, augmented 5th | Major 3rd + Major 3rd |
Evidence Bank
Chord: A combination of three or more pitches played simultaneously. It is the basic unit of harmony.
Triad: The most common type of chord, consisting of three notes—a root, a third, and a fifth.
Seventh Chord: A four-note chord built by adding a third on top of a triad. Its analysis is an extension of the principles used for triads.
Chord Quality: The classification of a chord based on its unique interval structure (e.g., major, minor). This structure gives the chord its characteristic sound.
Major Triad (M): A triad defined by a Major 3rd and Perfect 5th above the root. It is a stable, consonant sonority.
Minor Triad (m): A triad defined by a minor 3rd and Perfect 5th above the root. It is also stable and consonant.
Diminished Triad (°): A triad defined by a minor 3rd and diminished 5th above the root. It is an unstable, dissonant sonority.
Augmented Triad (+): A triad defined by a Major 3rd and augmented 5th above the root. It is also an unstable, dissonant sonority.
Skill Snapshots
Foundational Construction
Building a D Major triad: Start with the root D. A Major 3rd above D is F♯. A Perfect 5th above D is A. The resulting chord is D–F♯–A.
Building an f minor triad: Start with the root F. A minor 3rd above F is A♭. A Perfect 5th above F is C. The resulting chord is F–A♭–C.
Building a B diminished triad: Start with the root B. A minor 3rd above B is D. A diminished 5th above B is F. The resulting chord is B–D–F.
Structural Analysis
Rule: A major triad consists of a Major 3rd and a Perfect 5th. → Effect: The distance between the third and the fifth of the chord will always be a minor 3rd.
Rule: Both major and minor triads contain a Perfect 5th between the root and the fifth. → Effect: This shared interval gives both qualities a sense of acoustic stability and consonance.
Rule: Diminished and augmented triads feature a non-perfect fifth (diminished 5th or augmented 5th). → Effect: This altered fifth creates dissonance and a feeling of instability that seeks resolution.
Aural Identification
Baseline Sound: The major triad is consonant and often perceived as bright or open. It serves as a common point of stability in Western music.
Contrast 1 (Minor): The minor triad is also consonant and stable due to its perfect fifth, but its minor third gives it a character often described as somber or dark.
Contrast 2 (Diminished): The diminished triad is immediately identifiable by its dissonant and "tense" sound, which creates a strong pull toward resolution.
Continuity: The primary aural difference between a major and a minor triad is the quality of the third. The root and fifth are identical, providing a common frame of reference.
Common Misconceptions & Clarifications
Confusing the Third with the Triad: A chord with a minor third is not automatically a minor triad. A diminished triad also begins with a minor third; the quality of the fifth is the deciding factor.
Ignoring the Fifth: The quality of the fifth is just as important as the third. The difference between a minor triad (m3, P5) and a diminished triad (m3, d5) is only the fifth.
Assuming the Lowest Note is the Root: When chords are inverted (not in root position), the lowest sounding note may not be the root. To identify the quality, you must first rearrange the notes into a stack of thirds to correctly identify the root.
Spelling Errors: Remember that a Major 3rd plus a Major 3rd creates an augmented triad, not a "double major" one. Likewise, two minor thirds create a diminished triad.
Summary
A chord is a foundational harmonic element made of three or more notes. The most basic type, the triad, is built by stacking thirds above a root. The specific combination of intervals used—measured from the root to the third and the fifth—determines the chord's quality. The four primary triad qualities are major (Major 3rd, Perfect 5th), minor (minor 3rd, Perfect 5th), diminished (minor 3rd, diminished 5th), and augmented (Major 3rd, augmented 5th). Being able to accurately identify these qualities from a score and by ear is a non-negotiable skill for understanding the structure, function, and expressive power of harmony.