Chord substitution

Much of the European classical repertoire and the vast majority of blues, jazz and rock music songs are based on chord progressions.

Composers, songwriters and arrangers have developed a number of ways to add variety to a repeated chord progression.

There are many ways to add variety to music, including changing the dynamics (loudness and softness).

In J. S. Bach's St Matthew Passion, the chorale "Herzliebster Jesu" makes its first appearance in a straightforward harmonisation: Later, as the Passion Story draws towards its sombre conclusion, we find "a more chromatic and emotional setting of the melody" that passes through "no less than ten chords with grinding chromatic steps in the bass":[2] The well-known theme of the second movement of Joseph Haydn's String Quartet, Op.

[3] Hans Keller calls this "the fullest and richest statement"[4] of the famous melody: "In the second bar, for instance, there even is a turn to the relative minor":[5] The diminished triad can be used to substitute for the dominant seventh chord.

[7] Jazz musicians often substitute chords in the original progression to create variety and add interest to a piece.

Scott DeVeaux describes a "penchant in modern jazz for harmonic substitution.

The musician typically applies a sense of the musical style and harmonic suitability to determine if the chord substitution works with the melody.

As such, a performer or arranger who wished to add variety to the song could try using a chord substitution for a repetition of this progression.

When performed by the bass player, this chromatic root movement creates a smooth-sounding progression.

"Tritone substitutions and altered dominants are nearly identical...Good improvisers will liberally sprinkle their solos with both devices.

This technique is used in music such as bebop or fusion to provide more sophisticated harmony, or to create a new-sounding re-harmonization of an old jazz standard.

Also, jazz improvisers may use chord substitution as a mental framework to help them create more interesting-sounding solos.

In doing so, this implies the substitute chords over the original progression, which adds interest for listeners.

Tritone substitution: F ♯ 7 may substitute for C7, and vice versa, because they both share E ♮ and B ♭ /A ♯ and due to voice leading considerations.
C7 is transpositionally equivalent to F ♯ 7, the leading tones resolve inversionally (E–B ♭ resolves to F–A, A ♯ –E resolves to B–D ♯ )
F–C7–F, F–F ♯ 7–F, B–F ♯ 7–B, then B–C7–B
Bach, St Matthew Passion , No. 3, Chorale "Herzliebster Jesu"
Bach, St Matthew Passion , No. 3, Chorale "Herzliebster Jesu"
Bach, St Matthew Passion , No 46, Chorale "Herzliebster Jesu" different harmonization
Bach, St Matthew Passion , No. 46, Chorale "Herzliebster Jesu" different harmonization
Haydn, String Quartet Op. 76, No. 3, second movement, bars 1–2
Haydn, String Quartet Op. 76, No. 3, second movement, bars 1–2
Haydn, String Quartet Op. 76, No. 3, second movement, bars 80–81
Haydn, String Quartet Op. 76, No. 3, second movement, bars 80–81
Final two chords in the first progression are each preceded by their dominants in the second progression
ii7–subV7– IM7–I6 progression
vii o 7 as dominant substitute
♯ II o 7 as dominant substitute
The tritone substitution ii–subV–I in C creates the chromatic root movement D–D ♭ –C.
Contrast with the original ii–V–I progression in C , which creates the leading-tone B–C.
iii 7 as tonic substitute
vi 7 as tonic substitute
♭ III + as dominant substitute
"Backdoor ii–V" in C: IV 7 – ♭ VII 7 –I Play ⓘ . [ 15 ] Chord symbols for the conventional ii–V progression are above the staff, with the chord symbols for the substitution in parentheses.