Dominant (music) - Dominant Key in Tonal Modulation

Dominant Key in Tonal Modulation

The movement to the dominant was part of musical grammar, not an element of form. Almost all music in the eighteenth century went to the dominant: before 1750 it was not something to be emphasized; afterward, it was something that the composer could take advantage of. This means that every eighteenth century listener expected the movement to the dominant in the sense that would have been puzzled if did not get it; it was a necessary condition of intelligibility. —Charles Rosen (1972)

"Dominant" also refers to a relationship of musical keys. For example, relative to the key of C major, the key of G major is the dominant key. Music which modulates (changes key) often modulates into the dominant. Modulation into the dominant key often creates a sense of increased tension; as opposed to modulation into subdominant (fourth note of the scale), which creates a sense of musical relaxation.

The vast majority of harmonies designated as "essential" in the basic frame of structure must be I and V–the latter, when tonal music is viewed in broadest terms, an auxiliary support and embellishment of the former, for which it is the principal medium of tonicization. —Berry (1976)

The dominant chord itself is composed of the dominant (sol), the leading-tone (ti), and the supertonic (re) scale degrees. According to the rules of tonal resolution, both the leading-tone and the supertonic primarily resolve to the tonic. These two tones resolving to the tonic are strengthened by the dominant scale degree, which is a common tone between the tonic and dominant chords. The dominant may also be considered the result of a transformational operation applied to the tonic that most closely resembles the tonic by some clear-cut criteria such as common tones.