UC San Diego

This thesis explores the topic of musical pulse tracking and applies related techniques to the design of a pulse- aware looping system. The beginning chapter introduces the basic concepts of rhythm theory that provide a foundation for the discussion of pulse inference and advanced rhythmic techniques in a looping system. Next, the basic varieties of pulse-tracking algorithms are explained in relation to previous research, and a number of musical applications are identified. This leads into the discussion of a pulse tracking algorithm implemented by the author, which systematically varies the pulse period to find a candidate based on a phase-consistency score. An offline testing environment for quantifying and visualizing the behavior of event-based pulse-tracking algorithms is presented. After developing a testing strategy, the results from analysis of synthetic and performed examples are presented and discussed. Finally, the discussion turns to the author's design of a multi- channel pulse-aware looping system written in C++. It takes advantage of knowledge about pulse positions, allowing a user to quantize and sequence commands in relation to metric time units. The system can stay synchronized with a performer during changes in tempo, and the design includes features enabling exploration of advanced rhythmic concepts, such as multi-period cycles, polyrhythmic tempo relationships and acceleration-based phasing effects