Tritone (music)

Overview

The tritone is an interval that spans six semitones, or three whole tones, making it exactly half an octave. In equal temperament tuning it can be notated either as an augmented fourth (e.g., C to F♯) or as a diminished fifth (e.g., C to G♭); both spellings represent the same pitch distance. Because it divides the octave symmetrically, the tritone is one of the most dissonant intervals in common‑practice Western music, producing a sense of tension that traditionally seeks resolution.

In tonal harmony the tritone commonly appears within dominant seventh chords (V7) as the interval between the third and seventh of the chord, and it also features prominently in altered chords, diminished seventh chords, and as a melodic device in chromatic passages. Its distinctive sound has made it a useful tool for composers ranging from the Baroque period to modern jazz and metal.

History / Origin

The term “tritone” derives from the Greek words tri (three) and tonos (tone), literally meaning “three tones.” The interval was recognized in medieval theory as the “diabolus in musica” (the devil in music) because of its unsettling quality. By the Renaissance it was systematically avoided in strict counterpoint, yet composers such as Johann Sebastian Bach employed it for expressive effect. In the 20th century, the tritone became a hallmark of modernist and jazz idioms, most famously in the opening of Béla Bartók’s *Music for Strings, Percussion and Celesta* and in the altered dominant chords of bebop.

How It’s Used

In classical harmony, the tritone is a defining feature of the dominant seventh chord, leading the ear to resolve to the tonic. In jazz, it is often reharmonized as a “tritone substitution,” where a dominant chord a tritone away replaces the original, creating smooth voice leading. The interval also appears in rock and metal as a source of dissonance, for example in the opening riff of “Black Sabbath” or the “Stairway to Heaven” intro. In film scoring, the tritone can underscore tension, mystery, or the supernatural, as heard in the famous “Jaws” motif.

Why It Matters

The tritone’s inherent tension makes it a powerful compositional device for creating drama, surprise, or resolution. Its role in dominant seventh chords underpins much of functional harmony, while its use in tritone substitution expands harmonic possibilities in jazz improvisation. Notable examples include the opening of “Maria” from *West Side Story*, the theme from *The Simpsons*, and the altered dominant chords in Miles Davis’s “Freddie Freeloader.” Understanding the tritone helps musicians navigate dissonance, voice leading, and harmonic color across genres.

Common Misconceptions

Because the tritone can be spelled in two ways, it is often confused with other intervals or misunderstood in its function.

• Misconception: The tritone is the same as a perfect fourth.
  Correction: A perfect fourth spans five semitones, whereas a tritone spans six semitones; the tritone is more dissonant.
• Misconception: All tritone occurrences sound equally “evil.”
  Correction: Context determines perception; in a dominant seventh chord the tritone resolves smoothly, while an isolated tritone can sound harsh.