Musical note standardised at 440 Hz, lying in the octave containing notes from C (middle C) to B. The lowest note on most pianos is A, the highest C. The MIDI system for electronic musical instruments and computers uses a straight count starting with note 0 for C at 8.1758 Hz up to note 127 for G at 12,544 Hz. A written note can also have a note value, a code that determines the note's relative duration. In order of halving duration, they are: double note (breve); whole note (semibreve); half note (minim); quarter note (crotchet); eighth note (quaver); sixteenth note (semiquaver).;
Musical note for this note is 440 Hz, although this varies in actual practice (see History of pitch standards). The note-naming convention specifies a letter, any accidentals, and an octave number. Each note is an integer number of half-steps away from concert A (A). Let this distance be denoted "n". If the note is above A, then "n" is positive; if it is below A, then "n" is negative. The frequency of the note ("f") (assuming equal temperament) is then: For example, one can find the frequency of C, the first C above A. There are 3 half-steps between A and C