A modal architecture for artificial reverberation

Abstract

The method of analyzing an acoustic space by way of modal decomposition is well established. In this work, a computational structure employing modal decomposition is introduced for synthesizing artificial reverberation, implementing the modes using a collection of resonant filters, each driven by the source signal and summed in a parallel structure. With filter resonance frequencies and dampings tuned to the modal frequencies and decay times of the space, and filter gains set according to the source and listener positions, any number of acoustic spaces and resonant objects may be simulated. While convolutional reverberators provide accurate models but are inflexible and computationally expensive, and delay network structures provide only approximate models but are interactive and computationally efficient, the modal structure presented in this work provides explicit, interactive control over the parameters of each mode, allowing accurate modeling of acoustic spaces, movement within them and morphing among them. Issues of sufficient modal density, computational efficiency and memory use are discussed. Finally, models of measured and analytically derived reverberant systems are presented, including a medium-sized acoustic room and an electro-mechanical spring reverberator.