Altered Chords: Adding Color and Tension to Your Music

Summary:

Altered chords are a cornerstone of modern harmony, providing a rich palette of tension and release by chromatically modifying standard chord tones. This guide demystifies altered dominant chords, explaining their theoretical foundation, construction, and practical application. We'll explore the four core alterations, the powerful Altered Scale that contains them, and their use in jazz (II-V-I progressions), rock (the "Hendrix chord"), and reharmonization techniques like tritone substitution. With clear examples for piano and guitar, you'll learn how to wield these "spicy" chords to elevate your compositions and improvisations.

Keywords:

altered chords, altered dominant chords, chromatic harmony, jazz harmony, chord extensions, chord substitution, tritone substitution, harmonic tension, reharmonization, voice leading, altered scale, ii-V-I progression, modern harmony, 7#9 chord

Introduction: What Are Altered Chords?

Imagine a standard chord progression as a smooth, predictable road. Altered chords are the scenic detours—the moments of thrilling tension that make the arrival at your destination (the resolution) feel so much more satisfying. In essence, an altered chord is a special type of dominant 7th chord.

Here's the definition:

• It's a dominant 7th chord. It has a root, a major third, and a minor seventh (e.g., G7 has G, B, F).
• Its function is to resolve. It creates a strong pull towards a tonic chord (e.g., G7 wants to resolve to C).
• It contains one or more "altered" tensions. The 5th and/or 9th of the chord are chromatically raised or lowered.

This "alteration" creates a powerful dissonance that pulls strongly towards a point of rest. While central to the language of jazz, the influence of altered chords can be heard everywhere, from the impressionism of Debussy to the funk-rock of Jimi Hendrix and the complex scores of modern film music. Understanding them is a key step toward harmonic mastery.

The Function of Alteration: Creating Tension and Release

The magic of an altered chord lies in its function. The core of a dominant chord's pull comes from the tritone interval between its 3rd and 7th. By altering the 5th and 9th, we add even more notes that are a semitone (half-step) away from the notes of the resolution chord. This intensifies the pull and creates incredibly smooth voice leading.

Let's compare a standard G7 resolving to Cmaj7 with a G7alt. The altered notes create powerful melodic lines that lead directly to their destinations.

The Four Core Alterations

There are four primary alterations you'll encounter, targeting the 5th and 9th of a dominant chord. They can be used individually or combined.

• Flatted Ninth (b9): A very common alteration that adds a dark, dramatic tension. (e.g., in G7, the A becomes Ab).
• Sharpened Ninth (#9): Adds a complex, bluesy color. It contains both the major third and an enharmonic minor third (e.g., in G7, B is the major 3rd and A# is the #9, which sounds like Bb, the minor 3rd). This creates its signature "clash."
• Flatted Fifth (b5): Creates a tritone with the root, adding instability. (e.g., in G7, the D becomes Db). This is sometimes notated as a #11.
• Sharpened Fifth (#5): Creates a tense, augmented sound that pushes upward. (e.g., in G7, the D becomes D#). This is often notated as a b13.

The shorthand `G7alt` typically implies a dominant chord with any combination of these four tones. The specific choice depends on the melody and the desired voice leading. If the melody note over a G7 is an Ab, using a G7(b9) chord will provide beautiful support.

The Theory: The Altered Scale

So where do all these altered notes come from? They are neatly contained within a single scale: the Altered Scale. It has several names, including the Super-Locrian mode or, most usefully, the 7th mode of the melodic minor scale.

The formula for the altered scale is: Root, b9, #9, 3, b5, #5, b7.

For a G7alt chord, the G Altered Scale contains these notes:

G (R), Ab (b9), A# (#9), B (3), Db (b5), D# (#5), F (b7)

This one scale gives you the essential chord tones (Root, 3rd, 7th) and all four altered extensions, making it the perfect tool for improvising over `alt` chords. A common shortcut to find it: play the melodic minor scale starting a half-step above your root. For G7alt, use the A-flat Melodic Minor scale (Ab, Bb, Cb, Db, Eb, F, G) but start and end on G. You'll find it contains the same notes, just with different enharmonic spellings (e.g., Cb is B, Bb is A#).

Practical Applications and Voicings

1. In a Jazz II-V-I Progression

The II-V-I is the most common progression in jazz, making it the perfect place to apply altered dominants. The V chord is altered to create maximum tension before resolving to the I chord.

2. In Rock and Pop: The "Hendrix Chord"

The most famous altered chord in rock is the 7#9. Popularized by Jimi Hendrix in songs like "Purple Haze," it has a gritty, bluesy, and harmonically ambiguous sound because it contains both the major 3rd and the #9 (which is enharmonically equivalent to a minor 3rd). This beautiful clash gives it its signature bite.

3. Reharmonization: Tritone Substitution

Here's a powerful secret: any G7alt chord shares many notes with a Db7 chord. G and Db are a tritone apart. This allows you to substitute one for the other. The altered notes of G7 (Ab, Db) are the core chord tones (3rd and Root) of Db7. This is called a tritone substitution.

Instead of Dm7 - G7alt - Cmaj7, you can play Dm7 - Db9 - Cmaj7. The Db9 creates a smooth, chromatic bass line (D - Db - C) and resolves beautifully.

Practice Strategies

For Pianists: Essential Voicings

Jazz pianists often play rootless voicings. For a G7alt, the left hand covers the root and 7th (or just the root) , while the right hand plays the 3rd and the altered extensions. Here are two classic two-handed voicings for G7alt resolving to Cmaj7.

For Guitarists: Common Shapes

These shapes are movable. The root note is on the low E string (6th string). For the G versions shown, place your finger on the 3rd fret of the low E string.

          G7b9:    3x3434
          G7#9:    3x3444 (The "Hendrix" shape)
          G7b5#9:  3x3244
          G7#5b9:  3x3443
          

For All Musicians

• Isolate and Practice: Play a V-I progression (like G7-Cmaj7) repeatedly. First play the standard G7, then substitute different altered versions (G7b9, G7#9, etc.). Listen closely to the difference in tension and the feel of the resolution.
• Learn the Altered Scale: Practice the altered scale over a V-chord drone in all 12 keys. Connect the sound of the scale to the sound of the chord.
• Improvisation: When improvising over a II-V-I, try using only notes from the altered scale over the V chord. Focus on targeting chord tones of the I chord from the altered notes of the V chord.
• Transcription: Listen to your favorite jazz, fusion, or R&B solos and identify where altered dominant sounds are used. Transcribe these phrases to build your vocabulary. Innovators like Charlie Parker, John Coltrane, and Thelonious Monk are essential listening.

Conclusion: Your Path to Harmonic Richness

Altered chords can seem intimidating, but they are a logical and powerful extension of basic harmony. By understanding their function—to create intense, directional tension—and their origin in the altered scale, you unlock a new level of harmonic sophistication. Start by integrating them into familiar progressions like the II-V-I, explore reharmonization with tritone subs, and listen for them in the music you love. With practice, these colorful, complex sounds will become an intuitive and exciting part of your musical language.

References:

1. Levine, M. (1995). The Jazz Theory Book. Sher Music Co.

2. Nettles, B., & Graf, R. (1997). The Chord Scale Theory & Jazz Harmony. Advance Music.

3. Goodrick, M. (1987). The Advancing Guitarist. Hal Leonard.

4. Piston, W., & De Voto, M. (1987). Harmony (5th ed.). W. W. Norton & Company.

5. Coker, J. (1997). Elements of the Jazz Language for the Developing Improvisor. Alfred Music.