Accidental (in the bar)

Key signature or accidental?

On the page Reading music the distinction is made: if sharps or flats come right after the clef, they apply to the whole piece, that is the key. A single sign in the middle of the piece, an accidental, on the other hand applies only until the end of the bar. The exercise page Key Signatures calls mixing up the two one of the most common beginner mistakes.

The page Notation symbols is more precise about the sharp: it applies only to the exact note position, so the same line or space and the same octave, unless it is cancelled by a natural sign. The natural sign cancels a preceding sharp or flat and puts the note back to its original pitch. It acts for the rest of the bar. If in the next bar the same note is to sound again as originally notated, no natural sign is needed any more.

Examples

Guitar

• Etüde Nr. 7 Matteo Carcassi, op. 60 No. 7 · guitar · 2 pages

  No key signature at the start of the line. In bar 2 there is a sharp before G (G♯), later further sharps and a bracketed natural sign before F. All apply only until the respective barline.

Piano

• Menuett B-Dur BWV Anh. 118, from the Notebook for Anna Magdalena Bach · piano · 1 page

  Two flats in the key signature. In the second part natural signs appear before E: they cancel the E♭ of the key signature for one bar.

The most common accidental in minor is the raised seventh degree, in A minor the G♯. The article The leading tone explains the reason. The sign never appears at the start of the line, but always as an accidental in the bar. More under Harmonic minor.

Common mistakes

• Carrying the sign across the barline: It applies only until the barline.
• Meaning another octave as well: A sharp before F4 does not affect F5.
• Confusing key signature and accidental: What is written at the start of the line applies to the whole piece.