Flat (music)In music, flat (Italian bemolle for "soft B") means "lower in pitch". Flat is the opposite of sharp, which is a raising of pitch. In musical notation, flat means "lower in pitch by one semitone (half step)", notated using the symbol which is derived from a stylised lowercase 'b'. For instance, the music below has a key signature with three flats (indicating either [[E-flat major|E major]] or C minor) and the note, D♭ (musical note)|D, has a flat accidental.
Under twelve-tone equal temperament, D-flat (musical note)|D for instance is enharmonically equivalent to C-sharp (musical note)|C, and [[G-flat (musical note)|G]] is equivalent to [[F♯ (musical note)|F]]. In any other tuning system, such enharmonic equivalences in general do not exist. To allow extended just intonation, composer Ben Johnston uses a sharp as an accidental to indicate a note is raised 70.6 cents (ratio 25:24), and a flat to indicate a note is lowered 70.6 cents.
In intonation, flat can also mean "slightly lower in pitch" (by some unspecified amount). If two simultaneous notes are slightly out-of-tune, the lower-pitched one (assuming the higher one is properly pitched) is "flat" with respect to the other. Furthermore, the verb flatten means to lower the pitch of a note, typically by a small musical interval.
Key signaturesFlats are used in the key signatures of # F major / D minor (B) # B-flat major|B major / G minor (adds E) # [[E-flat major|E major]] / C minor (adds A) # [[A-flat major|A major]] / F minor (adds D) # D-flat major|D major / B-flat minor|B minor (adds G) # [[G-flat major|G major]] / [[E-flat minor|E minor]] (adds C) # C-flat major|C major / [[A-flat minor|A minor]] (adds F) The order of flats in the key signatures of music notation, following the circle of fifths, is B, E, A, D, G, C and F (mnemonics for which include Battle Ends And Down Goes Charles' Father and Before Eating A Doughnut Get Coffee First).
Related symbolsDouble flats also exist, which look like (similar to two flats, ) and lower a note by two semitones, or a whole step. The Unicode character 𝄫 (U+1D12B) in the Musical Symbols block represents the double-flat sign. Historically, in order to raise a double flat to a simple flat, it was required to use the notation . In modern scores it is acceptable to simply denote this with a single flat .
A quarter-tone flat or half flat, indicating the use of quarter tones, may be marked with various symbols including a flat with a slash () or a reversed flat sign (). A three-quarter-tone flat, flat and a half or sesquiflat, is represented by a half flat and a regular flat ().
Although very uncommon, a triple flat () can sometimes be found. It lowers a note three semitones.