Accidental (music) Accidental (music) In music, an accidental is a note of a pitch (or pitch class) that is not a member of the scale or mode indicated by the most recently applied key signature. In musical notation, the sharp (), flat (), and natural () symbols, among others, mark such notes—and those symbols are also called accidentals. In the measure (bar) where it appears, an accidental sign raises or lowers the immediately following note (and any repetition of it in the bar) from its normal pitch, overriding sharps or flats in the key signature. A note is usually raised or lowered
Key signature the signature. In the major key with four flats (B E A D), for example, the penultimate flat is A, indicating a key of A major. In this case each new scale starts a fifth "below" (or a fourth above) the previous one. A key signature is not the same as a key; key signatures are merely notational devices. They are convenient principally for diatonic or tonal music. The key signature defines the diatonic scale that a piece of music uses without the need for accidentals. Most scales require that some notes be consistently sharped or flatted. For example, the