Harmony – the sounding-together
While melody is the notes one after another, harmony is their at-the-same-time. It arises as soon as several notes sound together, and it decides the colour, the mood and above all the tension and resolution of a piece. Harmony is the building block that gives melody support, depth and direction.
From interval to chord
The smallest harmonic unit is two notes sounding at the same time – an interval. The basic feeling is already decided here: some combinations seem calm and settled in themselves (consonant), others full of friction and calling for continuation (dissonant). Neither is "better" – music lives precisely off the alternation: dissonance creates tension, consonance resolves it.
When three or more notes sound together, we speak of a chord. The basic building block is the triad: a root note, above it the third and the fifth. Whether the third is "major" or "minor" decides perhaps the most important difference in colour in all of music – major or minor.
Major and minor
Major sounds bright, open, often cheerful to most ears; minor darker, softer, often serious or melancholic. The difference lies in a single note: the third of the chord, which in minor is a semitone lower. That so small a shift has so large an effect is one of the most astonishing facts of music. What matters: this pairing – major "cheerful", minor "sad" – is a rough rule of thumb, not a rule. Countless pieces contradict it; the context is always decisive.
Rest, tension, resolution
Chords do not stand side by side without relationship – they have functions within a key. Three roles are enough for understanding: the tonic is home, the point of rest towards which everything strives. The dominant creates tension and positively calls for the return to the tonic. The subdominant leads away from rest and prepares this tension. From this triad of functions – away from home, build tension, back home – a large part of all music is built, from the folk tune to the pop song.
The sentences of harmony
Just as notes become melodies, chords become chord progressions (cadences). The classic closing turn subdominant – dominant – tonic works like a sentence that ends meaningfully; the ear feels a real close. From a few such building blocks whole songs can be accompanied – it is no accident that many pop songs get by with a handful of recurring chords. The circle of fifths shows vividly which chords lie close to a key and therefore fit together particularly well.
How harmony and melody work together
Harmony and melody are not a side-by-side but a together. The same melody can be placed over different chords and thereby completely change its character – a note that sounds bright and content over a major chord can suddenly seem longing over a minor chord. Conversely, harmony determines which melody notes are felt as "fitting" and restful and which as full of tension: a note belonging to the chord currently sounding seems released, a non-chord note creates friction that calls to be carried on. This play of chord notes and passing notes is one of the finest means of expression there is – and the reason why one and the same melody can be told anew each time in different harmonisations.
Hearing harmony consciously
You do not need to be able to name chords in order to hear harmony. It is enough to attend to two sensations: does the moment feel like tension that presses onward, or like rest that has arrived? And: is the colour rather bright (major) or dark (minor)? Whoever keeps these two questions running while listening will, after a short time, perceive the harmonic up and down of a piece – and understand why one passage touches, tenses or relieves.
More than triads
The triad is the basic building block, but harmony becomes truly rich only through extensions. Add a further note a third above a triad and a seventh chord arises – named after the interval of the seventh between the lowest and highest note. The most important of them is the dominant seventh chord: it sits on the dominant and contains a strong dissonance that positively presses to resolve into the tonic. You can hear it – this chord sounds "unfinished", it wants to go on. It is precisely this built-in pull that makes it the engine of countless closing turns, from Bach to today's pop song.
Seventh chords and further extensions (ninth, eleventh) are the reason why jazz and modern harmony sound so much more colourful than a pure triadic texture: every additional note brings a new nuance of tension between the poles of rest and urge.
The same chord, a different effect
A chord need not always sound with its root at the bottom. Put a different chord note in the bass and we speak of an inversion. The notes stay the same, yet the effect changes noticeably: a root in the bass seems stable and firm, an inversion more flowing and less final. Composers use this to lead a bass line smoothly – so that the bass moves in small steps instead of leaping in large jumps from root to root. For the ear a soft, singable foundation arises, even though the harmonies themselves stay the same. Whoever attends to the lowest voice while listening often discovers a little melody of its own in the bass.
From the what to the how
Rhythm, melody and harmony determine what sounds. How strongly or tenderly it sounds is shaped by the next building block.