The CNMAT Rhythm Research Group (CRRG) is dedicated to the study of expressive musical rhythm and the development of tools to measure, represent, construct, and perform expressive rhythm.
We represent equally-spaced temporal subdivisions with the "tatum" or "temporal atom". In our representation, each rhythmic event (e.g., the beginning of a note) occurs on a specified tatum. Some tatums indicate emphasized beats, and are shown as thicker, non-dashed lines. There can be more than one way to divide main beats into tatums; in this example there are two tatum grids, one with four tatums per beat and one with six tatums per beat.
Each note has a deviation amount indicating how far in time from the nominal tatum it actually occurs. We consider these fine-grained temporal deviations to be a key factor in expressive rhythmic performance, and we put these deviations on equal footing with other expressive musical parameters such as pitch and timbre.
Another kind of deviation from strict metronomic rhythm is a tempo curve that applies to the entire cell in conjunction with the deviations.
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