Music theory basics · updated 2026-08-16

OCTAVE

The interval between one pitch and another at double or half its frequency. The two notes share a name because the ear hears them as the same pitch class.

Close-up of handwritten sheet music and a pencil on a piano music desk

SOURCES AND CITATIONS

Free, primary references for octave — standards bodies, manufacturers, government offices and university course material.

Open Music Theory (opens in a new tab)
Stanford CCRMA — Music 320 notes (opens in a new tab)

RELATED TERMS IN MUSIC THEORY BASICS

Pitch
Interval
Scale
Key and key signature
Chord and triad
Chord progression
Tempo and BPM
Time signature

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