Hyperbole
Rhetorical figure of exaggeration; in music theory the heightening of affect through extreme intervals or dynamics.
What it means
Hyperbole (German Hyperbel) is originally a figure of rhetoric: the deliberate exaggeration that impresses a thought through overdrawing. In the musical doctrine of figures of the seventeenth and eighteenth centuries, numerous such terms were taken over from rhetoric to name musical turns and to explain their effect.
Bear in mind that the doctrine of figures forms no uniform system: the treatises of the time name different figures, use the same names for different things, and classify them differently. Whether and in what sense hyperbole is listed there should be checked against the sources.
Musical use
The underlying idea is nevertheless sound. The music of the Baroque understood itself as speech in notes: it was to depict affects and move the listener, and recognizable means were available for this. Among them are transgressions of the usual — a leap beyond the expected tonal space, a peak note outside the previous range, a particularly harsh dissonance, a sudden dynamic change. Such means work because they stand out from a norm; their effect presupposes that this norm has been established beforehand.
In the vocal texture, such turns regularly stand at places in the text that justify them: at words of pain, of breadth, of excess. The connection of word and note is the key to understanding.
In the Baroque doctrine of figures, hyperbole is usually connected with the exceeding of the usual ambitus of a voice, that is, an ascent to an unusual height. As a counterpart some teachers name the hypobole, the descent below the usual depth. Like other figures it was meant to clarify an affect or a word of the text.
Performance practice
Do not additionally show off conspicuous turns: an extreme leap or a sharp dissonance acts of itself, and the surroundings must stay calm so that it stands out. Prepare such places by deliberately taking back what precedes. And, with vocal music, read the text — it tells you why the music falls out of the frame at this spot.