Foundations reference
Octaves
An octave is the interval between one note and the next higher or lower occurrence of the same note name. Octave equivalence lets pitches feel closely related even when they occupy different registers.
Developing reference
Overview
When pitch frequency doubles, the result is one octave higher; when it halves, the result is one octave lower. The notes share a pitch-class identity while remaining distinct sounding pitches in different registers.
Construction
An octave spans twelve semitone steps in the common chromatic system and receives the interval name perfect octave. Written notation distinguishes individual octaves so a note can be located in a precise register.
Characteristics
Octave-related notes are strongly similar in identity, which is why melodies can often be moved between registers without losing their essential contour. Register still changes colour, range, physical location, and musical impact.
Applications
Octave recognition helps with tuning, reading, arranging, doubling lines, locating repeated notes, and organising a fretboard. It also provides a boundary within which interval and scale patterns repeat.