Intervals — the distance that carries the feeling
Semitones, the named intervals, and why a major third and a minor third change everything.
Foundations — notes, intervals, keys · 10 min read
An interval is simply the distance between two notes, counted in semitones — one key on the keyboard, black or white. Two semitones is a major second, three is a minor third, four is a major third, seven is a perfect fifth, twelve is an octave. That short list covers most of what you will use daily.
The reason intervals matter more than notes is that they are what your ear actually hears. A major third from C up to E and a major third from F# up to A# sound like the same relationship, moved. This is why a song can be transposed into a singer's range and still be the same song.
Two intervals do the heavy lifting emotionally. A major third (four semitones) sounds open and settled. A minor third (three semitones) sounds inward and darker. Nearly every chord you write will be labelled major or minor purely by which of those two sits at the bottom of it.
- —An interval is a distance in semitones, not a pair of note names.
- —Major third = 4 semitones, minor third = 3.
- —Transposing keeps the intervals, which is why the song survives.
Play C then E, then C then Eb, ten times each. Say 'major, minor' as you go until you can hear the switch without looking at your hands.
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