Accidentals indicate changes of pitch that are not indicated at the beginning of a song in the key signature. Accidentals remain in effect until the end of the measure where they are written. However, some 20th century composers use accidentals to affect only the pitch that they immediately precede.

The double sharp sign indicates that a pitch should be raised by two semi-tones

The sharp sign indicates that a pitch should be raised by one semi-tones

The natural sign indicates that a pitch should be played without alteration; it will cancel any other accidental markings.

The flat sign indicates that a pitch should be lowered by one semi-tones

The double flat sign indicates that a pitch should be lowered by two semi-tones

 

 

accidentals double sharp sharp natural flat double flt

WP Glossary Term Usage