Fundamentals
Reading Intervals at Sight: Generic and Specific
Naming an interval at sight takes two passes: count the staff positions first, then judge what the accidental does to the size.
Tritone
An interval of six semitones, spelled as an augmented fourth or a diminished fifth, such as F to B or B to F.
Also called: augmented fourth, diminished fifth, tritone interval
A tritone is an interval of six semitones, exactly half an octave. It is spelled either as an augmented fourth, such as F to B, or as a diminished fifth, such as B to F. In C major, F to B is the only tritone in the scale. In a dominant seventh chord such as G7, the B and F form a tritone that resolves inward to C and E. Because the interval lies between the third and seventh of the chord, it is strongly associated with tension in tonal music. The two spellings suggest different resolutions, so the choice of spelling is a harmonic decision.
The tritone, with ratio and ear tips
Related terms
- EnharmonicDescribes two notes or intervals that sound the same but are written differently, such as C♯ and D♭.
- DominantThe fifth degree of the scale, a perfect fifth above the tonic, which pulls strongly back toward the tonic.
- Diminished intervalAn interval one semitone narrower than a perfect or minor interval with the same letter names, such as B to F.
- Augmented intervalAn interval one semitone wider than a major or perfect interval with the same letter names, such as F to B.
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Harmony
Tritone Substitution: The subV7 Chord That Still Resolves
Replace any dominant with the dominant a tritone away: why subV7 works, how it smooths bass lines, and where jazz standards hide it.