Minor second in the context of "Consonance and dissonance"

In music, a step, or conjunct motion, is the difference in pitch between two consecutive notes of a musical scale. In other words, it is the interval between two consecutive scale degrees. Any larger interval is called a skip (also called a leap), or disjunct motion.

In the diatonic scale, a step is either a minor second (sometimes also called half step) or a major second (sometimes also called whole step), with all intervals of a minor third or larger being skips. For example, C to D (major second) is a step, whereas C to E (major third) is a skip.

In Western music theory, a major second (sometimes also called whole tone or a whole step) is a second spanning two semitones (Play). A second is a musical interval encompassing two adjacent staff positions (see Interval number for more details). For example, the interval from C to D is a major second, as the note D lies two semitones above C, and the two notes are notated on adjacent staff positions. Diminished, minor and augmented seconds are notated on adjacent staff positions as well, but consist of a different number of semitones (zero, one, and three).

The major second is the interval that occurs between the first and second degrees of a major scale, the tonic and the supertonic. On a musical keyboard, a major second is the interval between two keys separated by one key, counting white and black keys alike. On a guitar string, it is the interval separated by two frets. In moveable-do solfège, it is the interval between do and re. It is considered a melodic step, as opposed to larger intervals called skips.

In modern Western tonal music theory, a diminished second is the interval produced by narrowing a minor second by one chromatic semitone. In twelve-tone equal temperament, it is enharmonically equivalent to a perfect unison; therefore, it is the interval between notes on two adjacent staff positions, or having adjacent note letters, altered in such a way that they have no pitch difference in twelve-tone equal temperament. An example is the interval from a B to the C♭ immediately above; another is the interval from a B♯ to the C immediately above.

In particular, it may be regarded as the "difference" between a diatonic and chromatic semitone. For instance, the interval from B to C is a diatonic semitone, the interval from B to B♯ is a chromatic semitone, and their difference, the interval from B♯ to C is a diminished second.

In Western music theory, an augmented unison, augmented prime, or chromatic semitone is the interval between two notes on the same staff position (same letter) that differ by one chromatic alteration. For example, the intervals between B♭ and B♮, as well as C♮ and C♯, are augmented unisons.

In 12-tone equal temperament, the augmented unison is rendered by the semitone; in this case it is enharmonically equivalent to the minor second.