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"Chord" is easily read as "a few notes sounding together". But is any three notes struck at once a chord? No — by that reading any cluster would qualify. The real definition has two halves:
Three or more notes sounding together, stacked one third apart.
The second half does the work. It filters out arbitrary note groups and leaves the kind that has a definite structure, can be named, and can carry harmonic function.
Stacking thirds: how chords are generated
Start on any note and take every other note upward, and you pile up thirds:
| Layers | Name | Content | Example (from C) |
|---|---|---|---|
| two thirds | triad | root + third + fifth | C–E–G |
| three thirds | seventh chord | add the seventh | C–E–G–B |
| four or more | ninth / eleventh / thirteenth | keep stacking | C–E–G–B–D … |
A chord is named after its lowest stacked note (the root), and its topmost note says how far the stacking goes. So "dominant seventh" sounds mysterious and unpacks into "three thirds stacked on one root".
Three elements of a chord
| Element | Decides | Example |
|---|---|---|
| root | the chord's name | C–E–G is "a C chord" |
| quality | brightness and stability | major / minor / diminished / augmented |
| voicing | thickness and spacing | the same three notes squeezed low or spread over two octaves (see [[concept:chord-voicing |
Add inversion (which note is in the bass — see inversion and figured bass) and those four variables describe the great majority of chords.
Diagram: stacked thirds versus an arbitrary group
Listen: three faces of one chord
The same C major triad heard three ways: as a block, broken up (arpeggio), and spread wide across two octaves. Half a chord's character comes from its notes, the other half from how they are arranged.
Common misconceptions
- "Any three notes together make a chord." They must be stacked in thirds. Mixed intervals give a cluster, which cannot be named or carry function.
- "A chord has three notes." Two notes are an interval; three or more are chords, and sevenths, ninths and thirteenths are all chords.
- "A chord's root is its lowest note." After inversion the bass is not the root, yet the root is still the root (see inversion).
- "One set of notes sounds one way." Voicing and inversion make the same notes sound completely different (see voicing).
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- 和弦为三个或以上音同时发声、按三度叠置构成，属和声学通则
- 三度叠置以外的音群（如四度叠置、音块）属近现代用法，为通行和声学表述
Used for fact-checking only; all prose is original.