Several algorithms for finding the tonal center of a musical context are extant in the literature. For use in interactive music systems, we are interested in algorithms that are fast enough to run in real time and that need only make reference to the material as it appears in sequence. In this article, I examine a number of such algorithms and the ways in which their contribution to real-time algorithmic listening can be bolstered by reference to concurrent analyzers working on other tasks. Though as part of the discussion I review my own key finder, the focus here is on the coordination of published methods using control structures for multiprocess analysis and their application in performance.


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