Two notes are better than one: how harmony works

Sing a tune on your own and you have a melody. Sing it with a friend on exactly the same notes and you have unison. But when your friend sings different notes that fit with yours, something new happens: harmony.

Rounds: the easiest harmony

In a round, everyone sings the same tune, but groups start at different times. Because the tune was written so its lines fit on top of each other, the overlap makes harmony without anyone learning a new part. Rounds have been sung for hundreds of years, from church music in Europe to classrooms today.

Drones

A drone (also called a pedal) is one long, held or repeated note underneath the music. Bagpipes use drones, and so do many singers across the world. Over a drone on C, some notes sound restful and some sound as if they want to move. Change the drone to A and the same tune can suddenly feel darker.

Intervals

An interval is the distance between two notes. - Unison: both voices on the same note. - 3rd: two notes with one letter between them, like C and E. Sounds sweet and warm; this is the most common harmony line. - 5th: like C and G. Sounds strong and open. - 2nd: next-door notes like C and D. They rub against each other and create tension.

Chords

Put the 1st, 3rd and 5th notes together (C, E and G) and you have a chord: C major. Start on A instead (A, C, E) and you get A minor. Major often sounds bright; minor often sounds more thoughtful or sad. On the ukulele, a whole chord sits under one or two fingers.

Melody and bass

Many songs have three layers: melody on top, chords in the middle, and a bass line at the bottom. The simplest bass line plays the root of each chord (C under C major, A under A minor). When the bass moves, the harmony moves with it.

Listen as hard as you sing

Harmony only works when everyone listens. If you can't hear the other parts, you are probably too loud. Singers adjust their tuning and volume constantly, a skill called ensemble awareness.