2.2 Intervals

Number and quality

An interval is the distance between two pitches, named by a number (unison, 2nd, 3rd…octave) and a quality: perfect (P), major (M), minor (m), augmented (A), or diminished (d).

Perfect vs. major/minor

Unisons, 4ths, 5ths, and octaves can be perfect (or aug/dim). 2nds, 3rds, 6ths, and 7ths can be major or minor (or aug/dim) — never 'perfect.'

Common intervals

In C: C–E is a major 3rd; C–E♭ a minor 3rd; C–G a perfect 5th; C–F a perfect 4th. Lowering a major interval by a half step makes it minor.

Key terms

Interval

distance between two pitches (number + quality)

Perfect intervals

unison, 4th, 5th, octave

Major/minor intervals

2nds, 3rds, 6ths, 7ths

Qualities

P, M, m, Augmented, diminished

Examples in C

C–E major 3rd; C–G perfect 5th; C–F perfect 4th

Try an AP-style question

C up to E is a…

1. perfect fourth
2. minor third
3. major second
4. major third