Suomeksi | In English

Circle of notes, pitch classes, and symmetry

A pitch class is a set of all pitches with the same note name or its enharmonic equivalent. An example of this is that the notes E sharp, F, and G double flat are in all octaves.

Pitch classes are labelled with numbers 1-12; all C notes are labelled with 0, all D flats and C sharps with 1, and so on. In music analysis, it is commonplace to label another note, for example, the tonal centre of a composition, with a zero.

In a circle of notes, the pitch classes form a clock-face with the number 0 occupying the place usually taken by 12. It is possible to illustrate intervals, chords, and different scales with the help of a circle of notes. The symmetry of a note system can also be illustrated with the circle.

Click the buttons in order to see how the interval and chord structures change. The structure of a seven-note jazz minor scale is close to that of a whole note scale (6 notes) and a diminished scale (8 notes).

With the help of the circle of notes, it is easy to compare the common features of scales usually considered quite different. The concept of a pitch class is one of the fundamental ideas of musicology based on set theory, which began at the end of the 20th century. The circle of notes also helps us to illustrate even non-tonal pitch classes.