Jazz Chords and Their Variants
Beyond the Triad
超越三和弦
Pop and rock harmony lives mostly in triads — three-note chords built by stacking thirds (root, 3rd, 5th). Jazz takes this foundation and keeps stacking: add the 7th, the 9th, the 11th, the 13th. Each added note introduces a new color, a new tension, a new possibility for voice leading.
This post walks through the core jazz chord types, their variants, and why each one sounds the way it does.
Seventh Chords: The Jazz Foundation
七和弦：爵士的基石
The seventh chord is where jazz begins. By adding a note a seventh above the root, we get four-note chords with fundamentally different characters:
| Chord Type | Formula | In C | Sound |
|---|---|---|---|
| Major 7th (Maj7) | 1 3 5 7 | C E G B | Warm, dreamy, sophisticated |
| Dominant 7th (7) | 1 3 5 b7 | C E G Bb | Tense, bluesy, wants to resolve |
| Minor 7th (m7) | 1 b3 5 b7 | C Eb G Bb | Mellow, smooth, introspective |
| Half-diminished (m7b5) | 1 b3 b5 b7 | C Eb Gb Bb | Dark, unstable, yearning |
| Diminished 7th (dim7) | 1 b3 b5 bb7 | C Eb Gb Bbb(=A) | Mysterious, tense, symmetrical |
Major 7th (Maj7)
大七和弦 (Maj7)
The major 7th chord is the sound of sophistication. The interval between the root and the natural 7th is a major seventh — just a half step short of the octave. This near-octave creates a gentle, floating dissonance that never demands resolution.
\[C^{\Delta 7} = C + E + G + B\]You hear Maj7 chords everywhere in bossa nova, city pop, and ballad jazz. It’s the chord of a sunset over water — beautiful, complete, needing nothing.
Dominant 7th (7)
属七和弦 (7)
The dominant 7th is the engine of jazz harmony. The flatted 7th (Bb in C7) creates a tritone with the major 3rd (E) — the most dissonant interval in tonal music. This tritone desperately wants to resolve: E pulls up to F, Bb pulls down to A, and the whole chord resolves to F (or Fm).
\[C^7 = C + E + G + Bb\]This tension-resolution mechanism (V7 → I) is the backbone of jazz progressions. Without the dominant 7th, there is no ii-V-I.
Minor 7th (m7)
小七和弦 (m7)
The minor 7th softens the minor triad’s darkness with a gentle b7. The result is smooth and introspective — less dramatic than a plain minor chord, more complex than a major.
\[Cm^7 = C + Eb + G + Bb\]In jazz, m7 chords most commonly appear as the ii chord in a ii-V-I progression (e.g., Dm7 → G7 → CMaj7). They set up the dominant with a sense of gentle motion rather than urgency.
The ii-V-I Progression
ii-V-I 进行
If the Komuro progression is the heart of J-pop, then ii-V-I is the heart of jazz. Nearly every jazz standard contains this progression, often multiple times in different keys.
In C major:
\[Dm^7 \to G^7 \to C^{\Delta 7}\]Why does it work so well?
1. Stepwise root motion. D → G → C moves by fourths (or equivalently, down by fifths) — the strongest root motion in tonal harmony.
2. Guide tone voice leading. The 3rd and 7th of each chord (the “guide tones”) resolve by step:
- Dm7: F (3rd) and C (7th) →
- G7: F stays as b7, B replaces C as 3rd →
- CMaj7: E replaces F, B stays as 7th
This means only one or two notes move at each change, and they move by half step. The smoothest possible connection.
3. Tension arc. The ii chord is stable but questioning. The V7 is tense (tritone!). The I is home. It’s a complete narrative: departure → tension → resolution.
Minor ii-V-i
小调 ii-V-i
In minor keys, the ii-V-i uses altered chord qualities:
\[Dm^{7\flat 5} \to G^{7} \to Cm^7\]The half-diminished ii chord (m7b5) adds darkness. The V7 stays dominant — it must be dominant to provide the tritone resolution. The i is minor 7th instead of major 7th, giving a bittersweet arrival instead of a bright one.
Extended Chords: 9ths, 11ths, and 13ths
扩展和弦：九度、十一度与十三度
Jazz doesn’t stop at 7ths. By continuing to stack thirds above the 7th, we get extended chords that add increasing richness:
| Extension | Added Note | Character | |———–|———–|———–| | 9th | 2nd up an octave | Adds brightness and space | | 11th | 4th up an octave | Adds suspension, ambiguity | | 13th | 6th up an octave | Adds warmth, completeness |
The 9th Chord
九和弦
A dominant 9th chord takes the dominant 7th and adds the 9th (= 2nd, up an octave):
\[C^9 = C + E + G + Bb + D\]The added D doesn’t increase tension the way the b7 does — instead, it adds space and shimmer. The 9th is consonant with both the root and the 5th, so it blends in naturally while adding complexity.
Variants:
- b9 (C Db): darkens the chord dramatically, common over V7 in minor keys
- #9 (C D#): the famous “Hendrix chord” — simultaneously major and minor, raw and aggressive
- Maj9 (CMaj7 + D): dreamy and lush, a staple of neo-soul and city pop
The 11th Chord
十一和弦
The 11th (= 4th, up an octave) is tricky. On a dominant chord, the natural 11th (F over C7) clashes with the major 3rd (E) — they’re a half step apart. So jazz musicians typically either:
- Omit the 3rd, creating a suspended sound
- Sharp the 11th (#11 = F#), which avoids the clash and adds a bright, Lydian color
The #11 is one of the most distinctive jazz sounds — it appears constantly in modern jazz, fusion, and film scores. It suggests the Lydian mode (major scale with #4), which has an inherently “floating” or “otherworldly” quality.
On minor chords, the natural 11th works beautifully — there’s no clash with the b3:
\(Cm^{11} = C + Eb + G + Bb + F\)
The 13th Chord
十三和弦
The 13th (= 6th, up an octave) is the final extension. A full 13th chord technically contains all seven notes of the scale, though in practice, notes are omitted to keep voicings playable and clear.
\[C^{13} = C + E + (G) + Bb + (D) + (F) + A\]The 13th adds warmth and fullness — it’s the sound of a chord that contains everything. Dominant 13th chords (e.g., G13 resolving to CMaj7) are common in swing, big band, and gospel jazz.
The b13 (Ab over C7) darkens the chord and implies the altered scale, often used in minor key resolutions.
Altered Dominants
变化属和弦
The altered dominant is jazz’s ultimate tension chord. It modifies every available extension of a dominant 7th:
\[C^{7\text{alt}} = C + E + (G\sharp/Ab) + Bb + Db + D\sharp + (Ab)\]In practice, an altered chord uses some combination of b9, #9, #11 (= b5), and b13 (= #5). The result is maximum dissonance that resolves with maximum satisfaction to the I chord.
The altered scale (7th mode of melodic minor) provides all these tensions systematically: over G7alt resolving to CMaj7, you play Ab melodic minor — every note is either a chord tone or an altered extension of G7.
Voice Leading: Why Jazz Chords Connect
声部进行：爵士和弦为何能相互连接
The real magic of jazz harmony isn’t individual chords — it’s how they connect. Jazz voice leading follows a principle: move each voice as little as possible, ideally by step or half step.
Consider a simple ii-V-I with four-note voicings:
| Voice | Dm7 | G7 | CMaj7 |
|---|---|---|---|
| Soprano | C | B | B |
| Alto | A | G | G |
| Tenor | F | F | E |
| Bass | D | G | C |
The top three voices barely move — one note stays, two move by step. Only the bass makes the characteristic fourth-jump. This economy of motion is what makes jazz changes sound inevitable rather than arbitrary, even when the harmonies are complex.
Jazz Harmony in Pop Context
流行音乐中的爵士和声
Many pop and R&B producers borrow jazz voicings to add sophistication:
- Neo-soul (D’Angelo, Erykah Badu): heavy use of m7, Maj9, and #11 chords
- City pop (Tatsuro Yamashita, Mariya Takeuchi): Maj7 and 9th chords everywhere, often in ii-V-I patterns
- Lo-fi hip hop: the entire aesthetic is built on detuned Maj7 and m7 chords over slow beats
- J-pop ballads: Maj7 chords replacing plain major triads for emotional depth
The progression from pop triads to jazz 7ths to extended harmony is really a spectrum of harmonic density — more notes, more color, more possible connections between chords. Jazz simply lives further along that spectrum than most other genres.