In Western music, the expression "middle C" refers to the note "C" or "Do" located exactly between the two staves of the grand staff, quoted as C4 in note-octave notation (also known as scientific pitch notation). It also tends to be to the middle of a keyboard, and it is near the top of the male vocal range and the bottom of the female vocal range. For other uses, see Music (disambiguation). ... In musical notation, the staff or stave is a set of five horizontal lines on which note symbols are placed to indicate pitch and rhythm. ... The Grand Staff using both bass clef on the bottom and treble clef on top allows for four octaves of notation, counting the two high ledger lines for Soprano C and two ledger lines below bass clef for Deep C. It is known as the grand staff because the two... Note-octave notation is the convention of naming notes using its respective letter as well as the number denoting the octave the note is in. ... This article or section may be confusing for some readers, and should be edited to be clearer or more simplified. ... Human voices may be classified according to their vocal range — the highest and lowest pitches that they can produce. ...

Although C4 is commonly known by the expression "middle C", the expression is keyboard-specific and players of some instruments may refer to the note by another expression. For example, that note (C4) would be "low C" to the player of a Western concert flute (as it is in the lowest register of that instrument — see Vocal and instrumental pitch ranges), while C5 would be middle C. Nevertheless, the expression "middle C" is generally clear across instruments and clefs. The Western concert flute or C flute is a transverse (or side-blown) flute, a musical instrument of the woodwind family. ...

When calculated in equal temperament with a reference of A above middle C as 440 Hz, the frequency of the middle C note is approximately 261.6 hertz. See pitch (music) for a discussion of historical variations in frequency. An equal temperament is a musical temperament, or system of tuning, in which an interval, usually the octave, is divided into a series of equal steps (equal frequency ratios). ... The hertz (symbol: Hz) is the SI unit of frequency. ... Sine waves of various frequencies; the bottom waves have higher frequencies than those above. ... The hertz (symbol: Hz) is the SI unit of frequency. ... Pitch is the perceived fundamental frequency of a sound. ...

For the frequency of each note on a standard piano, see Piano key frequencies. This is a virtual piano with 88 keys tuned to A440, showing the frequencies, in cycles per second (Hz), of each note (i. ...

Position of Middle C on an 88-key keyboard