Of the total twelve notes (pitches) in music, five can be written in two ways. These represent the same notes, but are named differently depending on the musical context. They are called enharmonic notes and one example is C# and Db. On the piano, the enharmonic notes are found on the black keys.
Names of the common enharmonic notes
- C# (c sharp) or Db (d flat)
- D# (d sharp) or Eb (e flat)
- F# (f sharp) or Gb (g flat)
- G# (g sharp) or Ab (a flat)
- A# (a sharp) or Bb (b flat)
Explanation of the ten enharmonic notes
If the D note, for example, is raised one half-tone it should be referred to as D# and if it is lowered one half-tone it should be referred to as Db.
Another situation there the enharmonic notes occur are in scales. The notes in F Major, for example, are spelled F, G, A, Bb, C, D, E and not F, G, A, A#, C, D, E. Although Bb and A# are the same note, A# is incorrect in the context. The normal way of spelling scales is to only include the same letter once, when that is possible.
Names of other enharmonic notes
- Cb (c flat) or B
- Fb (f flat) or E
- B# (b sharp) or C
- E# (e sharp) or F
Explanation of these enharmonic notes
Cb is an uncommon note name. It represents the same note a B. The use of Cb leads often to misunderstanding, but the reason is usually the same as was mentioned above: it is a standard practice when spelling scales and sometimes chords. The notes in Ab Dorian, for example, are correctly spelled Ab, Bb, Cb, Db, Eb, F, Gb and not Ab, Bb, B, Db, Eb, F, Gb (using Cb and such notes can be perplexing; therefore, both practices are used on Pianoscales.org).
Chords that have several names whereas they shared the same notes are called enharmonic chords. Examples are Cm7 and Eb6:
Cm7: C, Eb, G, Bb
Eb6: Eb, G, Bb, C
Extra related to enharmonic chords are the diminished 7th, which only has four different set of notes. Cdim7, Ebdim7, Adim7 and Gbdim7, for example, consists of the same notes: C, Eb, Gb, A. This are reflected in the Diminished scales.