Accidental (music)

Lore & Background

The modern accidental signs derive from the two forms of the lower-case letter b used in Gregorian chant manuscripts to signify the two pitches of B, the only note that could be altered. The 'round' b became the flat sign, while the 'square' b diverged into the sharp and natural signs. The three principal symbols indicating whether a note should be raised or lowered in pitch are derived from variations of the small letter b: the sharp (♯) and natural (♮) signs from the square 'b quadratum', and the flat sign (♭) from the round 'b rotundum'.

An accidental is a symbol in musical notation that alters the pitch of a given note. The most common accidentals are the flat, which lowers a note by a semitone, and the sharp, which raises it by a semitone. The natural cancels a previous sharp or flat. Double flats and double sharps alter a note by two semitones; triple flats and triple sharps, altering by three semitones, are extremely rare. An accidental applies to the note immediately following it and to all subsequent instances of that same pitch within the same measure, unless canceled by another accidental. This effect ends at a barline, except when a note with an accidental is tied to the same note across the barline; in that case, the accidental continues for the tied note but does not apply to any later notes. If a note with an accidental is repeated in a different octave, modern notation requires a new accidental for clarity, though older conventions sometimes assumed the initial accidental applied across octaves. In atonal music, an alternative system is often used where accidentals affect only the note they directly precede, and naturals are not repeated for tied notes unless the tie spans a line or page break. Courtesy accidentals, often placed in parentheses, may be used to resolve ambiguities, such as after a mid-measure clef change or octave sign.

Reader's Guide

Accidentals are fundamental to Western musical notation, allowing composers to specify pitches outside the key signature. A sharp raises a note's pitch by a semitone, a flat lowers it by a semitone, and a natural cancels a previous accidental or reinstates the key signature. Double flats and double sharps alter the pitch by two semitones. Accidentals apply to subsequent notes on the same staff position for the remainder of the measure, unless canceled by another accidental or a barline, except when a note is tied across a barline. In atonal music, an alternative system of note-for-note accidentals is sometimes used, where accidentals affect only the notes they immediately precede. Courtesy accidentals, often in parentheses, may clarify ambiguities. Microtonal music has developed additional notation systems, such as those used by Turkish musicians to represent intervals smaller than a tempered semitone.

Did You Know?

• The modern accidental signs derive from the two forms of the lower-case letter b used in Gregorian chant manuscripts.
• A double flat or double sharp alters the pitch of a note by two semitones.
• In some atonal scores, an accidental is notated on every note, including natural notes and repeated pitches.
• Turkish musicians refined the European accidental system to notate scales using intervals smaller than a tempered semitone.

The Language of the Staff

Musical notation operates as a comprehensive symbolic language, where marks on a page encode virtually every dimension of performance. Beyond the basic pitch and duration of notes, the system communicates dynamics, articulation, tempo, metre, and structural form such as whether a section should be repeated. It even specifies granular performance details: which fingers to use, which keys or pedals to engage, whether a string should be bowed or plucked, and the direction of bow movement. The clef system anchors this language by assigning a specific pitch to a specific line of the staff, effectively defining the tessitura of the music. While historically clefs could sit on any line or even a space, modern practice has narrowed the palette to treble, bass, alto, and tenor clefs. A clef typically appears at the leftmost position on a staff, though a change in register can introduce a different clef elsewhere in the line.

Accidentals, Key Signatures, and the Microtonal Frontier

Accidentals serve as temporary pitch modifiers, altering the note that follows them on the same staff position within a measure unless a subsequent accidental cancels the effect. Key signatures take a broader approach, declaring which notes are to be played as sharps or flats throughout the music that follows, accommodating up to seven sharps or flats. A key signature with B-flat means every B in every octave becomes B-flat, eliminating the need for individual accidentals on those notes. A signature with no sharps or flats typically signals C major or A minor, though it can also simply mean accidentals will be applied as needed. Beyond the standard twelve-tone system, microtonal music presents a notation challenge with no universally accepted standard. Quarter tones are commonly indicated by a fraction one-quarter beside an upward or downward arrow, while 19 equal temperament—dividing a whole tone into three steps—avoids nonstandard symbols entirely by making sharps and flats non-enharmonic.

Rhythm, Duration, and the Pulse of Measures

In American musical parlance, note and rest values carry names that express their length as a fraction of a whole note—a half note spans half that duration, a quarter note one quarter, and so on. These rhythmic values slot into measures, the fundamental units of a uniform pulse. Time signatures govern this structure: the top number declares how many beats fill each measure, while the bottom number identifies which note value constitutes a single beat. Although any number of beats is theoretically possible, the overwhelming majority of music employs multiples of two or three, making 2, 3, 4, and 6 the most frequent top numbers. Similarly, while any note length could define a beat, the quarter note (bottom number 4) and eighth note (bottom number 8) dominate practice. This framework provides performers with a consistent grid for organizing rhythmic flow, and breaks in the notation signal pauses within that grid.

Fingers, Pedals, and the Particulars of Each Instrument

Musical notation extends well beyond the universal staff into instrument-specific conventions. Guitarists encounter a fingerpicking system derived from Spanish or Latin finger names, written above, below, or beside the relevant note. Piano players see pedal marks for sustain, applicable to the piano, vibraphone, and chimes, and may encounter English fingering in pre-1940 British tutors, where a plus sign denotes the thumb followed by numbers 1 through 4. Harp notation mirrors piano fingering but omits the number 5, since the little finger is not used in playing the harp. Cello and bass players use a circle-with-a-line symbol, or rarely a T, for thumb positions. Mallet percussion for four-mallet and six-mallet setups employs numbered indicators that may be reversed. Organ notation draws on a variety of abbreviations for its keyboards, varying across European languages.

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