Generating Artificial Reverberation via Genetic Algorithms for Real-Time Applications.

Edward Ly,Julián Villegas

doi:10.3390/e22111309

Abstract

We introduce a Virtual Studio Technology (VST) 2 audio effect plugin that performs convolution reverb using synthetic Room Impulse Responses (RIRs) generated via a Genetic Algorithm (GA). The parameters of the plugin include some of those defined under the ISO 3382-1 standard (e.g., reverberation time, early decay time, and clarity), which are used to determine the fitness values of potential RIRs so that the user has some control over the shape of the resulting RIRs. In the GA, these RIRs are initially generated via a custom Gaussian noise method, and then evolve via truncation selection, random weighted average crossover, and mutation via Gaussian multiplication in order to produce RIRs that resemble real-world, recorded ones. Binaural Room Impulse Responses (BRIRs) can also be generated by assigning two different RIRs to the left and right stereo channels. With the proposed audio effect, new RIRs that represent virtual rooms, some of which may even be impossible to replicate in the physical world, can be generated and stored. Objective evaluation of the GA shows that contradictory combinations of parameter values will produce RIRs with low fitness. Additionally, through subjective evaluation, it was determined that RIRs generated by the GA were still perceptually distinguishable from similar real-world RIRs, but the perceptual differences were reduced when longer execution times were used for generating the RIRs or the unprocessed audio signals were comprised of only speech.

Highlights

In most situations, sound is perceived within enclosures such as rooms, large or small venues, caves, etc
The goal was to determine whether or not there were perceptual differences between audio signals convolved with real-world IRs and artificial IRs generated with the Genetic Algorithm (GA)
A working prototype was developed for a plugin that uses GAs to create artificial reverberation

Summary

Introduction

Sound is perceived within enclosures such as rooms, large or small venues, caves, etc. These enclosures imprint their characteristics (i.e., their transfer functions) on the sound depending on where the sound source and the listener are located within the enclosure. The collection of early and late reflections is usually referred to as “reverberation” While this phenomenon is often detrimental to speech intelligibility [1], it is frequently desired in music production as an expressive tool [2]. Some of the most common techniques for digitally simulating reverberation involve the use of delay lines, comb filters, feedback delay networks, etc

Methods

Results

Conclusion