Shimmer reverberation with nonlinear feedback delay networks

Shimmer reverberation is an effect used in music production to deliver ethereal, pitch-shifted textures and evolving ambient soundscapes. This paper explores the synthesis of shimmer effects using the feedback delay network architecture, a popular real-time reverberator. We propose five distinct approaches for integrating nonlinear and time-varying operations into the feedback loop, focusing on expanding the harmonic content while adhering to energy preservation and stability criteria. Our approach can generate a wide range of sonic characteristics, from harmonically rich distortions to musically coherent pitch-shifted reverberation, while maintaining stability and controllable decay behavior. This work bridges physically inspired structures with creative, non-physical audio effect design to support the exploration of novel music production tools.