Major Ninth
Definition & Properties
The major ninth is a compound interval spanning an octave plus a major second. It provides an open, colorful sound essential to add9 chords, major ninth chords, and jazz extended harmony.
| Property | Value |
|---|---|
| Abbreviation | M9 |
| Semitones | 14 |
| Quality | Major |
| Just Ratio | 9:4 |
| Cents from Equal | +3.91 |
| Harmonic Character | open and airy |
Ear Training Reference
The Major Ninth (M9) is commonly recognized by the ascending motion of: Compound major second; add9 chord color.
Practice direction: ascending — sing from the lower note up by 14 semitones.
Note Pair Examples
| Note 1 | Note 2 | Interval | Semitones |
|---|---|---|---|
| C | D (+ octave) | Major Ninth | 14 |
| G | A (+ octave) | Major Ninth | 14 |
| D | E (+ octave) | Major Ninth | 14 |
| F | G (+ octave) | Major Ninth | 14 |
Intonation by Temperament
The Major Ninth measures 9:4 in just intonation (+3.91 cents from equal temperament). This deviation affects ensemble tuning and instrument voicing.
| Temperament | C4 (Hz) | D5 (Hz) |
|---|---|---|
| Equal Temperament | 261.626 | 587.330 |
| Pythagorean | 260.740 | 586.665 |
| Just Intonation | 261.626 | 588.658 |
Instrument Tuning Context
Compound intervals (14 semitones) span more than an octave and appear in extended harmony and orchestral voicings.
Chords & Scales Containing This Interval
The Major Ninth is present in all diatonic contexts. See the Chord Reference for chord types that incorporate this interval.
Scales
These scales include the Major Ninth as a structural interval: