Modal Analysis and Synthesis of the University of Michigan Lurie Carillon

As part of a recent University of Michigan Bicentennial initiative to promote electroacoustic composition for the campus’s two carillons, the university has released a set of audio recordings of the sixty Eijsbouts bells of the Robert & Ann Lurie Carillon. In support of that initiative, we present a modal analysis of these recordings, decomposing the sound of each bell into a sum of decaying sinusoids. Each sinusoid is characterized by a modal frequency, complex amplitude, and exponential decay rate. This analysis yields insight into the timbre of each individual bell as well as the entire carillon as an ensemble, and yields a powerful parametric synthesis model for contemporary composers to create novel bell-based electroacoustic timbres that are consistent with the sound of the Lurie Carillon. This synthesis model can be used in a number of ways. It can be used to resynthesize versions of the original bell recordings with a greatly reduced background noise. It can synthesize bell sounds that match the original timbre but are tuned to different scales or extend the range of the carillon. By applying a damping scale factor one can create bells that ring longer or shorter than the real bells. As part of this project, the raw modal analysis will be made available alongside reference implementations of Lurie-Carillon-based audio synthesis routines in several common computer music programming languages. Our hope is that this modal analysis and set of synthesis examples will provide a useful and inspirational resource for electroacoustic composers wishing to write music for the Lurie Carillon.