Interval (music)

Overview

An interval in music is the measured distance in pitch between two notes. It can be described numerically by the number of scale steps separating the notes, and more fundamentally by the ratio of their frequencies. Intervals are classified as harmonic when the notes sound simultaneously, and as melodic when they occur in succession.

Intervals serve as the building blocks of Western tonal harmony, providing the framework for chords, scales, and melodic motion. Their perceived consonance or dissonance influences tension and release within a piece, shaping the emotional contour of music across genres.

History / Origin

The concept of musical intervals dates back to ancient Greece, where philosophers such as Pythagoras discovered the mathematical relationships between string lengths and pitch. The term “interval” derives from the Latin “intervallum,” meaning a space or gap. Throughout the Middle Ages and the Renaissance, interval theory was codified in treatises on counterpoint and tuning, eventually becoming a central element of Common Practice Period harmony.

How It’s Used

Intervals appear in every musical style, from classical symphonies to jazz improvisation and pop songwriting. They are notated in staff notation by the relative positions of notes, and in lead sheets by the names of the intervals (e.g., perfect fifth, minor third). Instrumentalists use intervallic knowledge for tasks such as transposition, chord construction, and ear training.

Why It Matters

Understanding intervals enables musicians to analyze and create harmonic progressions, craft memorable melodies, and develop aural skills. Famous examples include the opening perfect fourth of Beethoven’s Fifth Symphony, the descending minor third motif in “Amazing Grace,” and the use of tritone substitution in jazz standards.

Common Misconceptions

Intervals are often confused with related concepts, leading to misunderstandings about their function and classification.

• Misconception: An interval’s size is the same as the number of semitones.
  Correction: While semitone count determines the interval’s size, quality (major, minor, perfect, augmented, diminished) also depends on its position within a scale.
• Misconception: All fifths sound the same in every tuning system.
  Correction: In just intonation a perfect fifth has a 3:2 ratio, whereas in equal temperament it is slightly tempered, affecting its perceived consonance.