A pitch class is one of the 12 chromatic notes named independently of octave

A pitch class names a note without specifying register: c, c#, d, d#, e, f, f#, g, g#, a, a#, b. There are exactly 12 of them, repeating in every octave. Combining a pitch class with a register gives a specific pitch (e.g., C4 = middle C). In live-coding intent vectors, key is expressed as a lowercase pitch class (‘c’, ‘f#’, ‘a’) so the framework can resolve it to any octave as needed. Reasoning at the pitch-class level keeps musical logic independent of the absolute register a voice ends up in.

Examples

The pitch class ‘c’ appears as C1, C2, C3, C4, C5… — all the same class, different octaves. Intent vector: key = ‘f#’.

Assessment

List the 12 chromatic pitch classes. Explain the difference between a pitch class and a pitch, and why intent vectors specify key as a bare pitch class.