Leading tone

In music theory, a leading-note (also subsemitone, and called the leading-tone in the US) is a note or pitch which resolves or "leads" to a note one semitone higher or lower, being a lower and upper leading-tone, respectively.

More narrowly, the leading tone is the seventh scale degree of the major scale, with a strong affinity for and leading melodically to the tonic (Benward and Saker 2003, 203). It is sung as ti in movable-do solfège. For example, in the C major scale (white keys on a piano, starting on C), the leading note is the note B; and the leading note chord uses the notes B, D, and F: a diminished triad. In music theory, the leading note triad is symbolized by the Roman numeral vii°. By contrast, an upper leading-tone (Berger 1987, 148; Coker 1991, 50), which leads down, may be found as the seventh of the dominant seventh chord, which leads to the third of the tonic chord (in C: F of a G7 chord leads to E of a CM chord). The upper leading-tone may also be found above the tonic, on D♭ in C.

According to Ernst Kurth (1913, 119–736) the major and minor thirds contain "latent" tendencies towards the perfect fourth and whole-tone, respectively, and thus establish tonality. However, Carl Dahlhaus (1990, 44–47) contests Kurth's position, holding that this drive is in fact created through or with harmonic function, a root progression in another voice by a whole-tone or fifth, or melodically (monophonically) by the context of the scale. For example, the leading note of alternating C chord and F minor chords is either the note E leading to F, if F is tonic, or A♭ leading to G, if C is tonic. In works from the 14th- and 15th-century Western tradition, the leading-note is created by the progression from imperfect to perfect consonances, such as a major third to a perfect fifth or minor third to a unison. The same pitch outside of the imperfect consonance is not a leading note.

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