Tritone (Augmented Fourth / Diminished Fifth)
Definition & Properties
The tritone divides the octave exactly in half, creating maximum dissonance. Called diabolus in musica historically, it is essential for dominant seventh chord tension and jazz harmony.
| Property | Value |
|---|---|
| Abbreviation | TT, A4, d5 |
| Semitones | 6 |
| Quality | Augmented |
| Just Ratio | 45:32 |
| Cents from Equal | -9.78 |
| Harmonic Character | maximum dissonance |
Ear Training Reference
The Tritone (Augmented Fourth / Diminished Fifth) (TT, A4, d5) is commonly recognized by the ascending motion of: The Simpsons theme; Maria (West Side Story).
Practice direction: ascending — sing from the lower note up by 6 semitones.
Note Pair Examples
| Note 1 | Note 2 | Interval | Semitones |
|---|---|---|---|
| C | F# | Tritone (Augmented Fourth / Diminished Fifth) | 6 |
| G | C# | Tritone (Augmented Fourth / Diminished Fifth) | 6 |
| D | G# | Tritone (Augmented Fourth / Diminished Fifth) | 6 |
| F | B | Tritone (Augmented Fourth / Diminished Fifth) | 6 |
Intonation by Temperament
The Tritone (Augmented Fourth / Diminished Fifth) measures 45:32 in just intonation (-9.78 cents from equal temperament). This deviation affects ensemble tuning and instrument voicing.
| Temperament | C4 (Hz) | F#4 (Hz) |
|---|---|---|
| Equal Temperament | 261.626 | 369.994 |
| Pythagorean | 260.740 | 371.251 |
| Just Intonation | 261.626 | 367.911 |
Instrument Tuning Context
Intervals smaller than a perfect fifth (6 semitones) are most sensitive to tuning in ensemble playing. Wind and string players adjust embouchure and finger pressure to lock in pure ratios.
Chords & Scales Containing This Interval
Chords
These chord types contain the Tritone (Augmented Fourth / Diminished Fifth) as a characteristic interval:
Scales
These scales include the Tritone (Augmented Fourth / Diminished Fifth) as a structural interval: