Key signature may consist of one or more sharps combined with one or more flats (such as a signature containing both F and B). Key signatures of this kind can be found in the music of Béla Bartók, for example. The effect of a key signature continues throughout a piece or movement, unless explicitly cancelled by another key signature. For example, if a five-sharp key signature is placed at the beginning of a piece, every A in the piece in any octave will be played as A sharp, unless preceded by an accidental (for instance, the A in scale 2 illustrated –
Scientific pitch notation frequencies, in other words, standard concert pitch and twelve-tone equal temperament). When a piano is tuned to just intonation, C refers to the same key on the keyboard, but a slightly different frequency. Mathematically, given the number formula_1 of semitones above middle C, the fundamental frequency in hertz is given by formula_2 (see twelfth root of two). Given the MIDI NoteOn number formula_3, the frequency of the note is normally formula_4 Hz, using standard tuning. Scientific pitch (q.v.) is an absolute pitch "standard", first proposed in 1713 by French physicist Joseph Sauveur. It was defined so that all Cs are