Musical intervals are the distance in pitch between two notes, measured in whole steps (UK: tones) and half steps (UK: semitones). They are the basic unit of harmony: scales, chords and melodies are built from them. This section gathers all the concepts: definition, classification by number and quality, consonance and dissonance, inversion, widening and narrowing.
Interval concepts
Musical Intervals
Full classification: number, quality and kind of intervals.
Harmonic and Melodic
Successive notes (melodic) versus simultaneous notes (harmonic), with examples.
Conjunct and Disjunct
Adjacent notes (2nd) versus leaps (3rd or more) and melodic motion.
Simple and Compound
Within the octave (simple) versus larger than an octave (compound).
Whole Step and Half Step
The two basic units of distance between scale notes.
Diatonic and Chromatic Half Step
The difference between half steps with different letter names and with the same letter name.
Unison and Enharmonic Notes
Notes with the same sound but a different name on the staff.
Inversion of Intervals
The rule of 9 and how quality changes when an interval is inverted.
Widening and Narrowing
How moving one note by an octave makes an interval wider or narrower.
Consonant and Dissonant
Intervals that rest or that create harmonic tension.
Frequently Asked Questions
What is a musical interval?
A musical interval is the distance in pitch between two notes, measured in whole steps and half steps. It is the basic unit of harmony: scales, chords and melodies are built from intervals.
How are intervals classified?
Intervals are classified by number (how many letter names they span: 2nd, 3rd, 4th, 5th, 6th, 7th or octave) and by quality (perfect, major, minor, augmented or diminished). They are also divided into simple and compound intervals.
What is the difference between a harmonic and a melodic interval?
A harmonic interval is formed when the two notes sound at the same time. A melodic interval occurs when the notes sound one after the other, forming a sequence.
How do you invert an interval?
To invert an interval, move the lower note up an octave (or the upper note down an octave). The number changes: an interval and its inversion always add up to 9. The quality changes too: major becomes minor, augmented becomes diminished, and perfect stays perfect.
What are consonant and dissonant intervals?
Consonant intervals sound stable and do not need to resolve: unison, octave, perfect 5th, and major and minor 3rds and 6ths. Dissonant intervals create tension and ask to resolve: 2nds, 7ths and the tritone (augmented 4th / diminished 5th). The perfect 4th is a special case: consonant in a melody and often treated as dissonant in harmony.