Questions: Jazz Reharmonization and Analysis

Question 1

Why does replacing G7 with D♭7 constitute a valid harmonic substitution in jazz?

• A. Both chords are built on roots a perfect fifth apart, creating smooth voice leading
• B. Both chords contain the same tritone (B and F), which defines dominant function and drives resolution
• C. D♭7 has a darker color that jazz musicians prefer for variety
• D. Both chords share the same scale and therefore the same characteristic tensions

Answer: (B)

The tritone B–F is the defining feature of G7: the interval between the third (B) and seventh (F) creates the chord's dominant tension and drives resolution to C. D♭7 also contains B and F (enharmonically C♭ and F) — the same tritone, just with the notes swapped in position. Because dominant function is determined by this tritone, not by the root, the two chords are functionally interchangeable. The substitution replaces descending-fifth bass motion (G→C) with half-step motion (D♭→C), creating the characteristic chromatic bass lines in Bill Evans–style playing.

Question 2

A melody note E is sustained while the harmony changes from D minor (where E is the ninth) to F major. What function does E serve in the F major chord?

• A. E is a 'wrong note' and must be avoided in the substitution
• B. E becomes the major seventh of F major — a valid tension — changing the harmonic meaning of the same pitch
• C. E remains the ninth of F major, because the interval relationship is preserved
• D. The substitution is invalid because E is not a chord tone of F major

Answer: (B)

This illustrates a fundamental principle of reharmonization: the melody note is fixed, and its function is reinterpreted by the new chord beneath it. E is the major seventh above F (the interval F–E), a standard accepted tension in jazz voicings. The pitch is unchanged; what changes is its relationship to the bass and its harmonic meaning. This reinterpretation — the same pitch as ninth in one context, major seventh in another — is what gives jazz reharmonization its capacity for harmonic surprise without melodic disruption.

Question 3

Tritone substitution characteristically produces descending half-step bass motion toward the tonic, in contrast to the descending fifth motion of the standard dominant-to-tonic resolution.

• T. True
• F. False

Answer: True

Standard dominant-to-tonic resolution moves the bass by a descending perfect fifth (G down to C, i.e., G7 → Cmaj). When G7 is replaced by its tritone substitute D♭7, the bass note D♭ resolves by descending a half step to C. This half-step bass motion is the audible signature of tritone substitution — it creates a smoother, more chromatic line that jazz musicians use to generate harmonic density while maintaining the functional direction of the progression.

Question 4

Reharmonization allows a performer to alter the melody notes as long as the underlying chord progression is structurally preserved.

• T. True
• F. False

Answer: False

Reharmonization works in exactly the opposite direction: the melody is the fixed element and the chords are the variable. The fundamental constraint is that each new chord must accommodate the existing melody note as a chord tone or accepted tension. Changing the melody is composition or arrangement, not reharmonization. This is why reharmonization analysis begins with the lead sheet melody and asks which chord substitutions can support it — not with the chords and asks which melodies could work.

Question 5

What four questions should an analyst ask when evaluating each chord substitution in a transcription, and why does this systematic framework matter?

Model answer: The four questions are: (1) Does the melody note work as a chord tone or accepted tension in the new chord? (2) Does the bass motion make sense — by step, fifth, or tritone? (3) Is the harmonic rhythm preserved? (4) What tonal center or mode does the substitution imply? The framework matters because it converts impressionistic reactions ('that sounds cool') into analytical claims that can be discussed, tested, and taught — distinguishing between hearing jazz harmony and understanding it.

These four questions target the four dimensions along which reharmonization operates: vertical fit (melody note compatibility), horizontal motion (bass voice leading), temporal structure (placement of chord changes), and tonal meaning (modal or tonal implication). A substitution can pass all four tests and still feel conventional, or fail one and work in context — but having explicit criteria lets the analyst explain *why* an unconventional choice succeeds or fails, which is the difference between impressionistic listening and rigorous harmonic analysis.