Modulation music: Encyclopedia II - Modulation music - Types of modulation

Modulation music - Types of modulation

There are several different types of modulation -- (these) modulations may be prepared or unprepared, smooth or abrupt. It is smoother to modulate to more closely related keys than to keys further away. Closeness is determined by the number of notes in common between keys, which provides more possible pivot chords, and their closeness on the circle of fifths. A modulation is often completed by a cadence in the new key, which helps to establish it. Brief modulations are often considered tonicizations.

Modulation music - Common chord modulation

Common chord modulation moves from the original key to the destination key (usually a closely related key) by way of a chord both keys share. For example, G major and D major share 4 chords in common: GMaj, Bmin, DMaj, Emin. This can be easily determined by a chart similar to the one below, which compares chord qualities. The I chord in G Major—a G major chord—is also the IV chord in D major, so I in G major and IV in D major are aligned on the chart.

Any chord with the same root note and chord quality can be used as the "pivot chord." However, chords that are not generally found in the style of the piece (for example, major VII chords in a Bach-style chorale) are also not likely to be chosen as the pivot chord. When analyzing a piece that uses this style of modulation, the common chord is labeled with its function in both the original and the destination keys, as it can be seen either way.

Modulation music - Enharmonic modulation

An enharmonic modulation is when one treats a chord as if it were spelled enharmonically as a functional chord in the destination key, and then proceeds in the destination key. There are two main types of enharmonic modulations: dominant seventh/augmented sixth, and diminished seventh -- by respelling the notes, any dominant seventh can be reinterpreted as a German or Italian sixth (depending on whether or not the fifth is present), and any diminished seventh chord can be respelled in multiple other ways to form other diminished seventh chords.

(Examples: C-E-G-Bb, a dominant 7th, becomes C-E-G-A#, a German sixth. C#-E-G-Bb, a C# diminished seventh, can also be spelled as E-G-Bb-Db, an E diminished seventh, G-Bb-Db-Fb, a G diminished seventh, and Bb-Db-Fb-Abb, a Bb diminished seventh.)

This type of modulation is particularly common in Romantic music, in which chromaticism rose to prominence.

Modulation music - Common-tone modulation

Common-tone modulation uses a sustained or repeated pitch from the old key as a bridge between it and the new key. Usually, this pitch will be held alone before the music continues in the new key. For example, a held F from a section in Bb major could be used to transition to F major.

Modulation music - Chromatic modulation

A chromatic modulation is so named because a secondary dominant or other chromatically altered chord is used to lead one voice chromatically up or down on the way to the new key. (In standard four-part chorale-style writing, this chromatic line will be in one voice.) For example, a chromatic modulation from C major to d minor:

In this case, the IV chord, FM, would be spelled F-A-C, V/ii, AM, A-C#-E, and the ii chord, dm, D-F-A. Thus the chromaticism, C-C#-D, along the three chords; this could easily be partwritten so those notes all occurred in one voice.

Modulation music - Phrase direct abrupt modulation

Phrase (also called direct or abrupt) modulation is a modulation in which one phrase ends with a cadence in the original key, and begins the next phrase in the destination key without any transition material linking the two keys. This type of modulation is frequently done to a closely related key -- particularly the dominant or the relative major/minor key. A common device in popular music, the "truck driver's gear change," is an abrupt modulation, usually to the key a semitone above, typically used to provide an "emotionally uplifting" finale.

Abrupt modulation is also common in forms with sharply delineated sections, such as theme and variations and many dance forms.

Modulation music - Sequential modulation rosalia

It is also possible to modulate by way of a sequence. The sequential passage will begin in the home key, and may move either diatonically or chromatically; harmonic function is generally disregarded in a sequence, or, at least, it is far less important than the sequential motion. For this reason, a sequence may end at a point that suggests a different tonality than the home key, and the composition may continue naturally in that key.

A sequence does not have to modulate; a modulating sequence is known as a rosalia.

Adapted from the Wikipedia article "Types of modulation", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki