The Tritone Interval (TT)
An interval is the distance between two notes, counted in semitones. Each of the thirteen simple intervals has its own page: reference songs that open with it, where it sits on the guitar fretboard, its inversion, and the chords built from it.
- The Unison (P1) — 0 semitones
- The Minor 2nd (m2) — 1 semitone
- The Major 2nd (M2) — 2 semitones
- The Minor 3rd (m3) — 3 semitones
- The Major 3rd (M3) — 4 semitones
- The Perfect 4th (P4) — 5 semitones
- The Tritone (TT) — 6 semitones
- The Perfect 5th (P5) — 7 semitones
- The Minor 6th (m6) — 8 semitones
- The Major 6th (M6) — 9 semitones
- The Minor 7th (m7) — 10 semitones
- The Major 7th (M7) — 11 semitones
- The Octave (P8) — 12 semitones
The tritone spans 6 semitones — maximum tension — three whole steps, splitting the octave exactly in half. It does not land on a major-scale degree from the tonic, which is exactly why it sounds so colorful — it lives outside the key. Inverted (the lower note moved up an octave) it becomes the tritone.
The classic way to internalize it: sing a song that opens with it — Maria (West Side Story) (the leap on "Ma-ri-"); The Simpsons (theme) (the opening "The Simp-sons"). You also hear the tritone inside chords built on it, like Dim, dim7, m7b5, 7#11. Then drill it on the ear trainer until you name it without thinking.