Related
There are five accidentals, but only one scope rule and three uses.
The five signs
| Sign | Name | Effect |
|---|---|---|
| ♯ | sharp | raises by a semitone |
| ♭ | flat | lowers by a semitone |
| ♮ | natural | cancels a previous sharp or flat |
| 𝄪 | double sharp | raises by two semitones (a whole tone) |
| 𝄫 | double flat | lowers by two semitones |
The double sharp and double flat look odd but are necessary: when a note has already been raised by the key signature (F♯, say) and you need to raise it again, you write 𝄪 — not G. The reason is the third use below.
One scope rule
An accidental applies only within its bar, to that pitch.
| Case | Rule |
|---|---|
| the same pitch later in the same bar | no need to repeat the sign |
| crossing into the next bar | the sign must be repeated (otherwise it reverts) |
| the same note name in another octave, same bar | a separate sign is required (strict practice) |
That last row is easily missed: an accidental governs that specific pitch, not "that note name in any octave". (Publishers differ in leniency; strict practice requires the extra sign.)
Three uses
1. Serving harmonic function (the commonest)
| Use | Example |
|---|---|
| raising the leading tone | in minor the seventh degree is raised to obtain dominant function (see [[concept:harmonic-minor |
| chromatic notes in secondary dominants | see [[concept:leading-tone-chord |
| chromatic passing motion | see [[concept:chromatic |
2. Altering the mode. The raised sixth and seventh of melodic minor are written with accidentals.
3. Enharmonic spelling (why double sharps and flats exist)
The same sounding pitch can be written in different ways, and the spelling carries harmonic meaning (see enharmonic spelling):
| Pitch | Possible spellings | What each means |
|---|---|---|
| sounding as G | G · F𝄪 · A𝄫 | G: the fifth degree; F𝄪: a raised F, the leading tone in G♯ minor; A𝄫: a lowered A |
So spelling is not a typesetting matter but a question of what role the note plays in the harmony — written as F𝄪, the reader knows at once that it resolves upward to G♯; written as G, that information is gone.
Diagram: one scope rule
Listen: natural and raised
Use interval to compare a major second with a minor second — the latter is exactly the effect an accidental usually produces. An accidental, heard, is a semitone shift.
Common misconceptions
- "An accidental lasts." Only within its bar; across a bar line it must be rewritten.
- "Double sharps are rare, so write the next note up." Spelling carries harmonic meaning. F𝄪 and G sound
- "An accidental just changes a pitch." It often serves harmonic function (raising a leading tone,
- "The same note name in another octave carries over automatically." Strict practice requires **a separate
alike, but in G♯ minor F𝄪 is the leading tone — writing G throws that away.
chromatic passing), not merely "changing a note".
sign**: the accidental governs that pitch. :::
Listen in the library
All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).
Sources
- 变音记号共五种（升 / 降 / 还原 / 重升 / 重降），作用于本小节内同高度的音，为记谱法通则
- 等音写作（重升 / 重降的使用）与和声意义的关联，为通行乐理与记谱规范表述
Used for fact-checking only; all prose is original.