diminished second
Inverseaugmented seventh
Other names
Interval class0
Just interval128:125[2]
12-Tone equal temperament0
Just intonation41.1

In modern Western tonal music theory, a diminished second is the interval produced by narrowing a minor second by one chromatic semitone.[1] In twelve-tone equal temperament, it is enharmonically equivalent to a perfect unison.[3]; 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.

Being diminished, it is considered a dissonant interval.[4]

Diminished second Play

Size in different tuning systems

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In tuning systems other than twelve-tone equal temperament, the diminished second can be viewed as a comma, the minute interval between two enharmonically equivalent notes tuned in a slightly different way. This makes it a highly variable quantity between tuning systems. Hence for example C is narrower (or sometimes wider) than D by a diminished second interval, however large or small that may happen to be (see image below).[citation needed]

Diminished second in quarter-comma meantone (also known as lesser diesis), coinciding with the interval from C to D, defined as the difference between m2 and A1 (117.1 − 76.0 = 41.1 cents). Play

In 12-tone equal temperament, the diminished second is identical to the unison (play), because the chromatic and diatonic semitones have the same size. In 19-tone equal temperament, which extends third-comma meantone, it is identical to the chromatic semitone and is a respectable 63.16 cents wide. The most commonly used meantone temperaments fall between these extremes, giving it an intermediate size.

However, in 53-tone equal temperament, which extends Pythagorean tuning, the interval actually shows a descending direction, i.e. a ratio below unison, and thus a negative size, going one step down. In general, this applies for all tunings with fifths wider than 700 cents.

The table below summarizes the definitions of the diminished second in the main tuning systems. In the column labeled "Difference between semitones", m2 is the minor second (diatonic semitone), A1 is the augmented unison (chromatic semitone), and S1, S2, S3, S4 are semitones as defined in five-limit tuning#Size of intervals. Notice that for 5-limit tuning, 1/6-, 1/4-, and 1/3-comma meantone, the diminished second coincides with the corresponding commas.

Tuning system Definition of diminished second Size
Difference between
Equivalent to Cents Ratio
Pythagorean tuning m2A1 Opposite of Pythagorean comma −23.46 524288:531441
1/12-comma meantone m2 − A1 Opposite of schisma −1.95 32768:32805
12-tone equal temperament m2 − A1 Unison 0.00 1:1
1/6-comma meantone m2 − A1 Diaschisma 19.55 2048:2025
5-limit tuning S3 − S2
1/4-comma meantone m2 − A1 (Lesser) diesis 41.06 128:125
5-limit tuning S3 − S1
1/3-comma meantone m2 − A1 Greater diesis 62.57 648:625
5-limit tuning S4 − S1
19-tone equal temperament m2 − A1 Chromatic semitone (A1 = m2 / 2) 63.16 :1
31-tone equal temperament m2 − A1 Lesser diesis 38.77 :1

See also


  1. ^ a b Bruce Benward and Marilyn Saker (2003). Music: In Theory and Practice, Vol. I, p. 54. ISBN 978-0-07-294262-0. Specific example of an d2 not given but general example of minor intervals described.
  2. ^ Haluska, Jan (2003). The Mathematical Theory of Tone Systems, p. xxvi. ISBN 0-8247-4714-3. Minor diesis, diminished second.
  3. ^ Rushton, Julian. "Unison (prime)]". Grove Music Online. Oxford Music Online.
  4. ^ Benward and Saker (2003), p. 92.