The roles of symmetrical measure groups in Mozart's piano sonatas

This dissertation focuses on the listener's expectation while listening to a phrase (or to other types of measure groups) that the phrase will be completed within a specific number of measures. The author discussess groups of examples from the piano sonatas in order to show that Mozart uses several techniques to create and contradict this expectation in subtle ways. Each of these techniques requires the listener to reinterpret a passage's rhythmic structure, which has a psychological effect that is dramatically appropriate at specific points within a movement. There are, for example, two techniques by which Mozart contradicts the listener's expectation that a cadence will occur at a particular moment. By immediately creating a new, equally strong expectation of when the cadence will occur, Mozart postpones and dramatizes the arrival of the cadence. Two other techniques draw the listener's attention to a modulating measure group in a dramatic way, underscoring the structural significance of the key toward which it moves.;A symmetrical measure group, as defined in the dissertation, has an exclusively duple-ordered structure; its length in measures is equal to some power of two (two, four, eight, etc.). Mozart's music often prompts the listener to expect a symmetrical measure group after hearing little more than half of such a group. The ease with which symmetrical structure can be implied allows Mozart to create and contradict the listener's rhythmic expectations with great subtlety. The contradiction of the listener's expectations often involves elision (abridgement) of the implied symmetrical group by a new measure group. Mozart's elisions of eight-bar groups frequently occur well before the final measure. It is likely that most listeners and performers feel the effects of such subtle elisions without being aware of their basis in symmetrical structure.;In the final chapter the author describes in greater detail the listener's gradual perception of a large symmetrical measure group. He then distinguishes between the analytic approach of the dissertation, based on the gradual perception, and several analytic approaches presented in the recent theoretical literature on rhythm.