Chords and feelings: how harmony changes the mood

Play the same melody over two different sets of chords and it can sound like two different stories: one sunny, one worried. That is the power of harmony, which means the notes that sound together underneath a tune.

What a chord is

A chord is three notes played at once. On a keyboard there is a simple rule: start on any white note, then play one, miss one, play one, miss one, play one. Start on C and you get C, E and G: the C major chord. The note you start on is the root, and it gives the chord its name.

Major and minor

Home and away

In the key of C major, the chord built on C is the tonic, or chord I. It feels like home. The chord built on G is the dominant, or chord V. It feels like it wants to go home. Loop C–G–C–G and you can hear the pull back to C. Many songs are built on just these two chords.

The loop that is everywhere

Four chords, C–G–Am–F, turn up in hundreds of pop songs. Play them in a different order, like Am–F–C–G, and the same four chords feel more serious. Producers try several orders before they choose.

From chords to bass

The easiest bass line uses the root of each chord, played low. When the chords go C–G–Am–F, the bass plays C, G, A, F. Give those notes a rhythm that matches the kick drum and suddenly the track feels solid. Then, if you like, add a note in between to make the bass walk from one chord to the next.