Changing metre

In the eighteenth century the constancy of notated metre was taken for granted by both composers and listeners. Virtually every piece or movement was written with one time signature from the beginning to the end. Exceptions to this rule occur in movements preceded by a slow introduction, which normally differs from the following main part of a movement not only as regards tempo but metre as well. However, within the same notated metre, the composed metre could change. One class of changes consisted in varying the period or phase of a composed metre. The former could be caused by imbroglio and hemiolas, the latter by syncopations. In contemporaneous music theory such metric changes were described as ‘confusions’ (Verwirrungen) by Joseph Riepel and ‘shifts’ (Rückungen) by Heinrich Christoph Koch. Because they referred to the mechanism of metric perception, they were accessible to all attentive listeners including less cultivated ones (Liebhaber). Another class of eighteenth-century metric manipulations relied upon the theoretical knowledge of the listener and hence could be appreciated only by Kenner able to properly interpret cues provided by the composer. Such manipulations involve a change of the level of the metrical hierarchy corresponding with the so-called ‘parts of the measure’ (Taktteile).

The most important cues used by eighteenth-century composers to indicate the metrical level of Taktteile are ending formulas represented by Einschnitte, Absätze and Kadenze. As repeatedly emphasized by authors of composition handbooks, caesura notes of these formulas must fall on a strong Taktteil (downbeat).