Definition
Accidentals modify the pitch of a written note. In the tempered system:
- Sharp (#): raises by a semitone.
- Flat (b): lowers by a semitone.
- Double sharp (x): raises by two semitones (F## sounds like G).
- Double flat (bb): lowers by two semitones (Bbb sounds like A).
- Natural (♮): cancels the previous accidental and restores the natural note.
The name of the note stays tied to the letter: F# is a raised F, not a lowered G. This distinction is needed to write scales and chords correctly (see Enharmonics).
Types of accidentals in notation
- In the key signature: they apply for the whole piece and in all octaves until the key signature changes. Order of sharps: F C G D A E B; order of flats: B E A D G C F.
- Temporary (incidental): written before the note, they last until the end of the bar and, by the traditional rule, only for that position on the staff (same octave). In modern practice (Elaine Gould, Behind Bars) it is recommended to repeat the accidental if the same note appears in another octave.
- Cautionary (or courtesy): in parentheses or plain, they remind you that the accidental of the previous bar no longer applies. They are optional but much appreciated by musicians.
- With a tie: if an altered note is tied across the barline, the accidental remains valid for the tied note, but not for the following notes of the new bar.
Double accidentals: when they are really needed
They are needed to respect the spelling of intervals and functions:
- In G# harmonic minor the leading tone is F## (F double sharp), not G: the scale must contain all seven letters (G# A# B C# D# E F##).
- The diminished seventh of C# minor (leading tone B#): B# D# F# A.
- In Eb minor the Neapolitan sixth (bII) is Fb major (Fb Ab Cb), with notes that look “strange” but are correct.
- To go back from a double sharp to a single sharp, today only # is written (the old ♮# spelling has fallen out of use).
Microtones (brief mention)
Arabic, Turkish, Persian, and contemporary music use quarter-tone accidentals (half sharp, half flat; in Arabic notation the slashed flat indicates about −50 cents). See the lesson on maqam.
Accidentals and function
A temporary accidental almost always signals something: an artificial leading tone (F# in C major leading to G: secondary dominant D7 → G), a modal borrowing (Ab in C major: Fm, Ab, Bb), a chromatic passing tone. A rule of thumb by ear: the # tends to rise, the b tends to fall.
Examples in pieces
- “Yesterday” (The Beatles, F major): Em7 and A7 appear and lead to Dm; the C# of A7 is the leading tone of the vi degree and creates the melancholy of the passage.
- Bach, Prelude in C major BWV 846: the F# in the first bars (D7/C going to G/B) and the subsequent return to F natural show the function of temporary accidentals and naturals.
Accidentals in the DAW
FL Studio's Piano roll shows note names only with sharps (C#, D#, F#…). When you transcribe into a score, rename according to the key: in F minor you will write Ab and Db, not G# and C#. MuseScore lets you respell a note enharmonically with the J key; Dorico and Sibelius have equivalent commands.
Exercise
- Write the scales of G# harmonic minor and Fb major using one letter per degree; count double sharps and double flats.
- Export the MIDI of the melody of one of your projects, open it in MuseScore, and correct the spelling of the accidentals according to the key.
- Find three altered notes in a piece you know and write next to each its function (secondary leading tone, borrowing, chromaticism).
Links
Key Signatures; Enharmonics; Secondary Dominants; Modal Interchange.