Modulation (music)
In music, modulation is the change from one tonality (tonic, or tonal center) to another. This may or may not be accompanied by a change in key signature (a key change). Modulations articulate or create the structure or form of many pieces, as well as add interest. Treatment of a chord as the tonic for less than a phrase is considered tonicization.
"Modulating" redirects here. For other uses, see Modulation (disambiguation).The quasi-tonic is the tonic of the new key established by the modulation. The modulating dominant is the dominant of the quasi-tonic. The pivot chord is a predominant to the modulating dominant and a chord common to both the keys of the tonic and the quasi-tonic. For example, in a modulation to the dominant, ii/V–V/V–V could be a pivot chord, modulating dominant, and quasi-tonic.
C♯–E–G–B♭ (dim. 7th), A–C♯–E–G (lowering the 7th a semitone and respelling as a modulating dom. 7th), D–F♯–A (quasi-tonic) leads to the key of D major—a parallel modulation (though not enharmonic). Enharmonically: C♯–E–G–B♭, A–C♯–E–F (Ger. aug. 6th), C♯–E–G♯ (quasi-tonic) modulates to C♯ minor—a major seventh modulation/half-step descending.
Significance[edit]
In certain classical music forms, a modulation can have structural significance. In sonata form, for example, a modulation separates the first subject from the second subject. Frequent changes of key characterize the development section of sonatas. Moving to the subdominant is a standard practice in the trio section of a march in a major key, while a minor march will typically move to the relative major.
Changes of key may also represent changes in mood. In many genres of music, moving from a lower key to a higher often indicates an increase in energy.
Change of key is not possible in the full chromatic or the twelve tone technique, as the modulatory space is completely filled; i.e., if every pitch is equal and ubiquitous there is nowhere else to go. Thus other differentiating methods are used, most importantly ordering and permutation. However, certain pitch formations may be used as a "tonic" or home area.
Popularity[edit]
The popularity of the key change varies with musical fashion over time. In Western popular music, from the 1960s to the 1990s, about one quarter of number-one hits on the Billboard Hot 100 featured a key change, but only one number-one hit in the 2010s had one.[25]
Other types[edit]
Though modulation generally refers to changes of key, any parameter may be modulated, particularly in music of the 20th and 21st century. Metric modulation (known also as tempo modulation) is the most common, while timbral modulation (gradual changes in tone color), and spatial modulation (changing the location from which sound occurs) are also used.
Modulation may also occur from a single tonality to a polytonality, often by beginning with a duplicated tonic chord and modulating the chords in contrary motion until the desired polytonality is reached.