Key signature key signatures showing sharps or flats on both octaves for notes which fall within the staff. An accidental is an exception to the key signature, applying only to the measure and octave in which it appears. Although a key signature may be written using any combination of sharp and flat symbols, the most common series of thirteen homogeneous key signatures—ranging from six flats to six sharps, with each successive flat or sharp placed on the note a perfect fifth below or above, respectively, the previous one—is assumed in much of this article. A piece scored using a single diatonic key
F (musical note) the key signature, in order to represent a diatonic, rather than a chromatic semitone; writing an F with a following F is regarded as a chromatic alteration of one scale degree (E and F do not sound the same, except in some tunings that define the notes in that way). F (musical note) F is a musical note, the fourth above C. It is also known as fa in fixed-do solfège. It has enharmonic equivalents of E and G, amongst others. When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of