Perfect Octave Interval

1Composition: what it contains

Semitones

12

Abbreviation

P8

Inversion

perfect unison

Consonance

perfect consonance

2Appearance: diagrams and sound

3Indications: what it is used for

The octave defines note names: notes an octave apart share the same letter. It is used in octave doubling (bass and piano left hand, octave melodies in jazz guitar and rock), in power chords with the octave added, and in the range of scales. Male and female voices singing the same melody are usually an octave apart. Harmonics at the twelfth fret on a guitar sound an octave above the open string.

4Dosage: how to practise it

On guitar, two strings up and two frets higher (three frets higher across the third and second strings), or twelve frets on one string. On piano, eight white keys counting both ends. Sing a note and then the octave above or below. Practise octave melodies on guitar at 60–90 BPM, muting the string in between. On bass, play octave patterns in disco and funk grooves. Train with an ear trainer, distinguishing octaves from sevenths and ninths.

Train it in the ear trainer

5Warnings and common mistakes

Do not confuse it with a unison: same letter name, different register. In voice leading, parallel octaves between independent voices are avoided in classical writing, though doubling is fine. An octave slightly out of tune sounds hollow or beating; check tuning. Some beginners count the octave as seven steps; it is eight letter names including both ends, twelve half steps.

6Other presentations available

• Perfect Unison Interval
• Minor Second Interval
• Major Second Interval
• Minor Third Interval
• Major Third Interval
• Perfect Fourth Interval
• Tritone Interval
• Perfect Fifth Interval
• Minor Sixth Interval
• Major Sixth Interval
• Minor Seventh Interval
• Major Seventh Interval