Major ninth

The major ninth (M9) spans 14 semitones. It combines octave space with a major-second quality, creating an open, bright extension used widely in modern harmony.

Construction and spelling

M9 is built as an octave plus a major second, for example C-D an octave higher. It can also be read as a compound major second. The spelling preserves ninth-function context in extended chords.

Harmonic and melodic usage

Harmonically, M9 appears in add9 and major/minor ninth sonorities, adding color without severe dissonance. Melodically, it gives broad contour and lift. It balances clarity and richness in voicing.

Examples

• Add9 chord textures in pop, jazz, and cinematic writing
• Extended tonic and subdominant colors
• Wide melodic skips with airy character

In practice

Practice M9 as both compound interval and chord extension. Compare M9 with M2 to hear the same quality in different registers. This improves voicing decisions and interval recognition.