Audio: accidental (0:05)

Figure: accidental

accidental plays a melody on a flute. The accidental figure shows two different notations:

  • The top score has no key signature and notates using accidentals only.
  • The bottom score uses the key signature of A major and notates using accidentals as well.

An accidental is a symbol in a score that modifies the pitch of a note:

  • A flat (b) lowers the pitch of a note by a semitone.
  • A sharp (#) raises the pitch of a note by a semitone.
  • A natural cancels out the previous effect of a sharp or flat.

The effect of a sharp or flat lasts for a single bar only and affects all notes of a similar pitch that follow in that bar. When the bar ends the sharpened or flattened note reverts back to its normal pitch. A natural is used to cancel the effect of a sharp or flat within a bar.

The effect of a key signature lasts to the end of a piece of music or until the next key signature change.

Modulation in music is signalled in a score with an accidental or a change in key signature or both together. An accidental is usually indicative of short-term modulation, a change of key signature is usually a sign of long-term modulation.