Harmony & Chords

A chord is more than several unrelated notes

Harmony asks how pitches work together in a musical context. A triad, in the Western tonal convention used here, contains three pitch classes arranged as a root, a third and a fifth. A pitch class groups pitches that differ by whole octaves. In this twelve-semitone model, different spellings such as C-sharp and D-flat can name the same pitch class. The root names the chord, even when a different chord tone is placed lowest.

You can explore a chord as a set of labelled cards before hearing it. Keep note collection, spacing and timing separate: a simultaneous chord and the same notes played one after another have a related collection but a different texture. A diagram shows selected relationships; it cannot reproduce the complete sound.

Worked example: change one interval

Use a twelve-semitone number model with C at 0. C major contains C, E and G at positions 0, 4 and 7. Its lower gap is four semitones and its upper gap is three. C minor uses C, E-flat and G at 0, 3 and 7: the lower gap is three and the upper gap four. Only the middle position moved, while root and fifth stayed fixed.

Now compare C–E–G with E–G–the next C, at 4, 7 and 12. Reducing each position by whole octaves gives the same pitch classes 4, 7 and 0. This is an inversion of the triad, rather than a new root named E. The lowest pitch matters to the voicing, but it does not automatically rename every chord.

Connections between chords add context

An invented sequence C major → F major → G major → C major uses C–E–G, F–A–C, G–B–D, then C–E–G. C is shared by the first two chords, and G by the first and third. On paper, circling shared tones suggests one way a composer could connect changes. It does not establish that a listener will find the sequence convincing.

There is no universal rule that a major chord always feels cheerful or a minor chord always sad. Instrument, spacing, rhythm, musical tradition and surrounding events affect interpretation. These triad names describe this convention; they do not rank other systems of combining pitches.

Use a constrained comparison

If your question is about inversion, keep the pitch classes fixed and change only their order or octaves. If your question is about major and minor, keep the root and fifth fixed while changing the third. Naming the variable makes the explanation clearer. You can record a prediction in words without needing to perform, use an app or persuade anyone else to share your response.