Back to alphabetical overview – click here
Perfect Fourth – Definition
A perfect fourth is an interval spanning four letter names and five semitones. It is one of the fundamental intervals in Western music.
What is a Perfect Fourth?
The perfect fourth is considered a perfect interval, along with the unison, perfect fifth, and octave. It appears in melodies, scales, chords, and harmonic progressions across virtually every musical style.
In harmonic contexts, a perfect fourth above the bass often functions as a suspension that resolves to a major or minor third. It is also the foundation of quartal harmony, in which chords are built by stacking fourths instead of thirds.
How is a Perfect Fourth used in piano playing?
Pianists use perfect fourths in melodies, suspended chords, quartal voicings, and modern jazz, gospel, and contemporary harmony. Stacking fourths creates an open, spacious sound that differs from the traditional harmony built on thirds.
Understanding the perfect fourth helps pianists recognize interval patterns, construct chords, and explore a wider range of harmonic textures.