Elementary Modulation

Modulation is passing from one key to another. There are two essentials
1) A cadence in the new key (usually some form of perfect)
2) The appearance of at least one note which belongs to the new key but not to the old.

Modulation may be gradual or abrupt.

Gradual Modulation
Gradual modulation passes through a pivot chord ( a chord that is common to both the scales).
- If the only pivot chord available is the root of the new key, then it should appear in a difference inversion from that used in the cadence.
- Pivot chords in second inversion should be avoided.
- If there is a chromatic alternation in a note as a result of modulation, then care must be taken that both these notes do not occur in the same part with just one note intervening. It gives an ugly effect.

Abrupt Modulation
This is also referred to as Transition. A chord present in the old key but not in the new, is abruptly followed by a chord that is present in the new key but not in the old. Both these chords will have a note in common. There will generally be chromatic movement in one of the parts.
- BE CAREFUL WITH DOWNWARD CHROMATIC MOVEMENTS: Chromatic movement up is common. Chromatic movement down is only good to the 7th of a dominant seventh or from major 3rd to minor 3rd of the same chord.
- AVOID FALSE RELATIONS. In dealing with transitions, false relations must be avoided. This is is the bad effect experienced when the a note in one part appears chromatically altered in another part.
- EXCEPTIONS TO FALSE RELATIONS: There are two cases where apparent false relation has no bad effect.
:: If the root of the second chord is the 3rd of the first chord. (eg. moving from C major to E major chord).
:: If the second of the two notes concerned is the 7th of a dominant 7th. (eg in modulating from C to F7, the E is one part of C and Eb in another part in the F7 is ok).