The names of the notes

Western music names twelve notes: C, C♯, D, D♯, E, F, F♯, G, G♯, A, A♯ and B. After B comes C again, an octave higher. The five notes with a sharp or a flat are the black keys of a piano, and each has two names: C♯ is also D♭. A number after the name says which octave: C4 is middle C.

All 12, with their other names

Seven letters, five in between

The white keys of a piano carry the seven letters, A to G. Between most pairs of letters there is a black key, a semitone above the lower letter and a semitone below the upper one. Between E and F, and between B and C, there is none, because those pairs are already a semitone apart. Seven and five make twelve.

Sharps and flats

A sharp (♯) raises a note by a semitone, and a flat (♭) lowers it by one. So the black key between C and D is C sharp, and also D flat. Two names for one key are called enharmonic. In written music the choice follows the key: a piece in A major writes C♯, one in A flat major writes D♭. To the ear, and to anyone naming a note heard on its own, they are the same note.

Octave numbers

The same letter comes round every twelve notes, each time at twice the frequency. Scientific pitch notation numbers each round, starting from C, so the C nearest the middle of a piano is C4, the one above it C5, and B3 is the note just below middle C. A4, the note orchestras tune to, is 440 Hz. Every note's frequency is in the frequency chart.

Pitch class

All the Cs together, whatever their octave, are one pitch class. There are twelve. When someone with absolute pitch names a note, they are naming its pitch class: they hear "C", and the octave is a separate question. Training for absolute pitch trains the twelve pitch classes, which is why it mixes octaves on purpose.

German names, and others

German calls a sharp by adding -is and a flat by adding -es or -s: Fis is F sharp, Es is E flat. And German B is English B flat, while English B is German H. Much of Europe and Latin America uses fixed do syllables, do re mi fa sol la si, which are set out in fixed do and movable do.

How Solfeto writes them

Solfeto uses letter names, with sharps by default. Flats are a setting. The names change on the screen and nothing else does: the training is the same twelve pitch classes either way.