Modal Interchange

Week 5

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The Plan for Today

• Review Natural Minor Modal Interchange• Review – Subdominant Minor Function• Review – Tonic Minor Function• Other Modal Interchange Chords

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Natural minor modal interchange

• Borrowing chords and scale tones from natural minor is a common method for embellishing major key systems

• This is achieved by using the same tonal center on which the major scale is based. (The parallel minor)

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Modal interchange:

•Increases the choices of cadential patterns through the use of subdominant minor chords•Colors the major key tonic functions with the alternative tonic minor chords•Establishes pivot functions that can create implied or actual modulations up a minor 3rd

•Provides reharmonization possibilities through functional substitution

Parallel major and minor

• Please examine page 48 of your Harmony 4 text

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• To insure that minor key structures will create an expectation to resolve in major:– The modal interchange chord should be

prepared or preceded by the major key sound– The 3rd and/or 6th degree of the major scale

must either replace its minor scale counterpart or be optionally available

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Subdominant and tonic minor

• The functions of subdominant minor and tonic minor are derived from the relative major

• Chords containing the b6 in minor are subdominant minor chords

• Chords without the b6 (containing the b3) are tonic minor

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Activity

• What are the subdominant minor functioning chords from natural minor?

• What are the tonic functioning chords from natural minor?

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Subdominant minor function

• Any parallel minor chord that contains the b6 scale degree as either its root, 3rd, 5th or 7th has subdominant minor function

• The b6 also corresponds to the 4th scale degree in the relative major.

• I.e. the b6 in C natural minor is Ab - the 4th scale degree in Eb major is Ab

• The b6 scale degree represents nontonic sound.

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The IVm chord• The IVm chord is considered the basis of SDM• This is because either the minor 7 or the major 6

degree is available on the IVm triad• The IVm6 creates a tritone that is found on other

nontonic modal interchange chords

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Chord scales

• The chord scales for IVm7 and bVImaj7 are the only chord scales that remain unaltered when used in modal interchange– IVm7 = dorian– bVImaj7 = lydian

• All other modal interchange chord scales will contain either the 3rd or 6th from the parallel major scale as an alteration to their original chord scales

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Tonic minor function

• Any parallel minor chord that does not contain the b6 scale degree as a chord tone has tonic minor function

• The b3 scale degree characterises the Tonic Minor function

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Other Modal Interchange Chords

• IIm7b5 – V7(b9) – derived from parallel harmonic minor

• Parallel dorian minor offer the possibility of Im7 – IV7.

• The IV7 typically resolves to Imaj7

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