Harmony
System of chord connections.
What it means
Harmony (German Harmonik) designates the study of sonority and of the connection of sonorities with one another. It asks not only how a chord is built but above all how chords follow one another: which connections have a goal, which remain open, how tension arises and how it is released. Thereby it is, alongside melody and rhythm, one of the three basic dimensions of music theory.
Musical use
The tonal system rests on a gradient. The tonic (I) is the point of rest, the dominant (V) aims at it with its leading tone, the subdominant (IV) leads away from it and prepares the dominant. From this order results the cadence, from the cadence the articulation of a movement: half cadences leave open, full closes conclude, deceptive cadences feign an ending and lead on. Secondary dominants direct the same gradient temporarily to another degree, modulations shift the centre entirely.
Historically this order is a development: the polyphony of the Middle Ages arises from the leading of voices, not from chord sequences; only with the figured bass of the Baroque does the sonority itself move to the centre. In the nineteenth century increasing chromaticism stretches the system to its limits, in the twentieth other orders come alongside — modality, quartal harmony, pandiatonicism, free surfaces of sound.
Harmony is to be distinguished from counterpoint, which considers the same music from the individual voices. Both views describe the same texture.
Other names
In German, Harmonie is used partly with the same meaning, partly more narrowly: for a single sonority or for the feeling of euphony. In addition, Harmonie also designates a wind ensemble, the Harmoniemusik. Harmonik by contrast means the totality of the sonorities and their connections in a piece or style, Harmonielehre the teaching of it.
Performance practice
Analyse a piece before you study it: where do the cadences lie, where does the key change, which passage is the harmonic climax? This decides phrasing and dynamics more than any marking entered. Play the harmonies once as a plain chord sequence without figuration — the construction of the texture then becomes directly audible.