Perfect Fourth Interval

1Composition: what it contains

Semitones

5

Abbreviation

P4

Inversion

perfect fifth

Consonance

perfect consonance

2Appearance: diagrams and sound

3Indications: what it is used for

The distance between most adjacent strings on guitar and all strings on bass in standard tuning. It appears in sus4 chords, quartal voicings in modal jazz, the 4–3 suspension, and the IV chord relationship to I. Melodically it opens many anthems, wedding marches and calls. The circle of fourths (the circle of fifths counterclockwise) is how jazz progressions often move. A perfect fourth inverted becomes a perfect fifth.

4Dosage: how to practise it

On guitar and bass, play the same fret on two adjacent strings (except between the third and second strings on guitar). On piano, five half steps. Sing the first and fourth notes of a major scale. Train ascending and descending fourths with an ear trainer three to five minutes daily, and stack fourths on piano to hear quartal harmony. Play a bass line moving in fourths around the circle.

Train it in the ear trainer

5Warnings and common mistakes

Do not confuse it with the augmented fourth (tritone), which is one half step larger. Between the third and second strings of a guitar in standard tuning the interval is a major third, so same-fret shapes change there. In classical harmony, the fourth above the bass is treated as a dissonance needing resolution. Spell it with letters four apart; an augmented third sounds the same but is spelled differently.

6Other presentations available

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