Short Answer
Overview
The major sixth is an interval that spans nine semitones (or nine half steps) between two pitch classes. In the diatonic scale, it is the distance from the tonic to the sixth degree (for example, C to A). The interval is considered consonant, though less stable than the perfect fifth or octave, and it carries a warm, lyrical character that composers often employ for expressive melody lines and harmonic color.
In just intonation the major sixth corresponds to a frequency ratio of 5:3, producing a pure sound that differs slightly from the equal‑tempered version used in most modern Western instruments. The interval can also appear as an inverted minor third, since inverting a major sixth (upward) yields a minor third (downward) and vice versa.
History / Origin
The term “major sixth” originates from medieval modal theory, where intervals were classified as “major” or “minor” based on their size relative to the diatonic scale. The concept was codified in the treatises of theorists such as Guido of Arezzo (11th c.) and later refined during the Renaissance by theorists like Gioseffo Zarlino, who described the 5:3 ratio as a pure major sixth. Its use became widespread in the common‑practice period (Baroque through Romantic eras) as composers explored richer harmonic language.
How It’s Used
Major sixths appear in a variety of musical contexts. In melody, they often create a sense of lift or yearning, as heard in folk songs and pop ballads. Harmonically, a major sixth can function as part of a “sixth chord” (e.g., C6 = C‑E‑G‑A) or as an added tone in jazz voicings, providing a sweeter alternative to the dominant seventh. The interval is notated either by its interval name (M6) or by the specific notes on staff, and it is common in vocal music, string passages, and wind instrument lines where smooth melodic leaps are desired.
Why It Matters
Understanding the major sixth is essential for musicians because it influences voice leading, chord construction, and melodic contour. The interval underpins many well‑known melodies, such as the opening of “My Funny Valentine” (C to A) and the chorus of “Somewhere Over the Rainbow.” In harmony, the major sixth adds richness to triads, and in jazz it is a staple of “major‑sixth” and “minor‑sixth” chord extensions that shape the genre’s characteristic sound.
Common Misconceptions
The major sixth is the same as a minor sixth.
A major sixth spans nine semitones, while a minor sixth spans eight; they have different pitch relationships and harmonic functions.
All six‑note intervals sound dissonant.
The major sixth is classified as a consonant interval in both historical theory and modern perception, though it is less stable than perfect intervals.
FAQ
How many half steps are in a major sixth?
A major sixth consists of nine half steps (semitones) between the lower and upper notes.
Can a major sixth be used in chord construction?
Yes; the major sixth is often added to triads to form sixth chords (e.g., C‑E‑G‑A) and appears in many jazz voicings as an extension.
What is the difference between a major sixth and an octave plus a major sixth?
An octave plus a major sixth is a compound interval called a major thirteenth; it spans 21 semitones, whereas a simple major sixth spans only nine semitones.
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