Intervals · Step 11
Seconds
The smallest intervals are the ones melodies are mostly made of. One semitone is a minor second: the two notes of the Jaws theme, so close they grind against each other. Two semitones is a major second, the ordinary step from one lettered note to the next — “Happy Birthday” climbs one going into “Birthday”, and so does almost every scale you have ever heard.
They are easy to tell from a third but surprisingly easy to confuse with each other, because both feel like “the next note”. The clue is tension: the minor second leans hard on the note beside it; the major second sits comfortably. Two buttons this time, and the gap between them is a single semitone.