Percussion Synthesis using Loopback Frequency Modulation Oscillators

In this work, we apply recent research results in loopback frequency modulation (FM) to real-time parametric synthesis of percussion sounds. Loopback FM is a variant of FM synthesis whereby the carrier oscillator “loops back” to serve as a modulator of its own frequency. Like FM, more spectral components emerge, but further, when the loopback coefficient is made time varying, frequency trajectories that resemble the nonlinearities heard in acoustic percussion instruments appear. Here, loopback FM is used to parametrically synthesize this effect in struck percussion instruments, known to exhibit frequency sweeps (among other nonlinear characteristics) due to modal coupling. While many percussion synthesis models incorporate such nonlinear effects while aiming for acoustic accuracy, computational efficiency is often sacrificed, prohibiting real-time use. This work seeks to develop a real-time percussion synthesis model that creates a variety of novel sounds and captures the sonic qualities of nonlinear percussion instruments. A linear, modal synthesis percussion model is modified to use loopback FM oscillators, which allows the model to create rich and abstract percussive hits in real-time. Musically intuitive parameters for the percussion model are emphasized resulting in a usable percussion sound synthesizer.