Musical note indicated by placing the symbols in the key signature, which then apply implicitly to all occurrences of corresponding notes. Explicitly noted accidentals can be used to override this effect for the remainder of a bar. A special accidental, the natural symbol , is used to indicate an unmodified pitch. Effects of key signature and local accidentals do not accumulate. If the key signature indicates G, a local flat before a G makes it G (not G), though often this type of rare accidental is expressed as a natural, followed by a flat () to make this clear. Likewise (and more
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