Minor Ninth
Definition & Properties
The minor ninth is a compound interval spanning an octave plus a minor second. It creates a strikingly sharp dissonance used for dramatic effect in jazz and orchestral writing.
| Property | Value |
|---|---|
| Abbreviation | m9 |
| Semitones | 13 |
| Quality | Minor |
| Just Ratio | 32:15 |
| Cents from Equal | +11.73 |
| Harmonic Character | sharp dissonance (compound) |
Ear Training Reference
The Minor Ninth (m9) is commonly recognized by the ascending motion of: Compound minor second; strong dissonance.
Practice direction: ascending — sing from the lower note up by 13 semitones.
Note Pair Examples
| Note 1 | Note 2 | Interval | Semitones |
|---|---|---|---|
| C | C# (+ octave) | Minor Ninth | 13 |
| G | G# (+ octave) | Minor Ninth | 13 |
| D | D# (+ octave) | Minor Ninth | 13 |
| F | F# (+ octave) | Minor Ninth | 13 |
Intonation by Temperament
The Minor Ninth measures 32:15 in just intonation (+11.73 cents from equal temperament). This deviation affects ensemble tuning and instrument voicing.
| Temperament | C4 (Hz) | C#5 (Hz) |
|---|---|---|
| Equal Temperament | 261.626 | 554.365 |
| Pythagorean | 260.740 | 556.875 |
| Just Intonation | 261.626 | 558.135 |
Instrument Tuning Context
Compound intervals (13 semitones) span more than an octave and appear in extended harmony and orchestral voicings.
Chords & Scales Containing This Interval
The Minor Ninth is present in all diatonic contexts. See the Chord Reference for chord types that incorporate this interval.
Scales
These scales include the Minor Ninth as a structural interval: