Pitch class

In music theory, a **pitch class** refers to a group of all pitches that are a whole number of octaves apart from each other. In other words, all the notes that have the same name, regardless of which octave they are in, belong to the same pitch class. For example, the pitch classes for C include all Cs, such as C4 (middle C), C5, C3, and so on. Each pitch class can be represented by a note name (e.