Seconds

Although there are only two possible natural second qualities (major or minor), seconds spelled with accidentals can be one of four qualities: major, minor, diminished, or augmented. Example 14-1 illustrates the four qualities and their relative sizes in semitones.

Example 14-1

Note that an augmented second (+2) is one semitone larger than a major second, while a diminished second (o2) is one semitone smaller than a minor second.

As the arrows in the table suggest, increasing the size of a major second by a semitone will produce an augmented second. Decreasing the size of a major second by a semitone will produce a minor second. Increasing the size of a minor second by a semitone will produce a major second. Decreasing the size of a minor second by a semitone will produce a diminished second.