Modern musical symbols
Musical symbols are the marks and symbols, used since about the 13th century in the musical notation of musical scores, styles, and instruments to describe pitch, rhythm, tempo and, to some degree, its articulation (a composition in its fundamentals).
Clefs define the pitch range, or tessitura, of the staff on which it is placed. A clef is usually the leftmost symbol on a staff. Additional clefs may appear in the middle of a staff to indicate a change in register for instruments with a wide range. In early music, clefs could be placed on any of several lines on a staff.
Musical note and rest values are not absolutely defined, but are proportional in duration to all other note and rest values. The whole note is the reference value, and the other notes are named (in American usage) in comparison; i.e., a quarter note is a quarter of the length of a whole note.
Durations shorter than the 64th are rare but not unknown. 128th notes are used by many composers, including Mozart and Beethoven; 256th notes occur in works by Vivaldi, Mozart and Beethoven. An extreme case is the Toccata Grande Cromatica by early-19th-century American composer Anthony Philip Heinrich, which uses note values as short as 2,048ths; however, the context shows clearly that these notes have one beam more than intended, so they should really be 1,024th notes.
The name of very short notes can be formed as 2n + 2th note, where n is the number of flags on the note.
Accidentals modify the pitch of the notes that follow them on the same staff position within a measure, unless cancelled by an additional accidental.
Key signatures define the prevailing key of the music that follows, thus avoiding the use of accidentals for many notes. If no key signature appears, the key is assumed to be C major/A minor, but can also signify a neutral key, employing individual accidentals as required for each note. The key signature examples shown here are described as they would appear on a treble staff.
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