Perceptual Decorrelator Based on Resonators
Jon Fagerström, Nils Meyer-Kahlen, Sebastian J. Schlecht and Vesa Välimäki
Companion page for the paper "Perceptual Decorrelator Based on Resonators" published in the proceedings of DafX25, Ancona, Italy.
The published paper can be accessed here.
Abstract
Decorrelation filters transform mono audio into multiple decorrelated copies. This paper introduces a novel decorrelation filter design based on a resonator bank, which produces a sum of over a thousand exponentially decaying sinusoids. A headphone listening test was used to identify the minimum inter-channel time delays that perceptually match ERB-filtered coherent noise to corresponding incoherent noise. The decay rate of each resonator is set based on a group delay profile determined by the listening test results at its corresponding frequency. Furthermore, the delays from the test are used to refine frequency-dependent windowing in coherence estimation, which we argue represents the perceptually most accurate way of assessing interaural coherence. This coherence measure then guides an optimization process that adjusts the initial phases of the sinusoids to minimize the coherence between two instances of the resonator-based decorrelator. The delay results establish the necessary group delay per ERB for effective decorrelation, revealing higher-than-expected values, particularly at higher frequencies. For comparison, the optimization is also performed using two previously proposed group-delay profiles: one based on the period of the ERB band center frequency and another based on the maximum group-delay limit before introducing smearing. The results indicate that the perceptually informed profile achieves equal decorrelation to the latter profile while smearing less at high frequencies. Overall, optimizing the phase response of the proposed decorrelator yields significantly lower coherence compared to using a random phase.
Optimized Decorrelators
Sound examples demonstrating the sound quality of the resonator-based decorrelator using the three different target group delay profiles. Please use headphones for the correct binaural experience.
You can download the proposed group delay profile version of the decorrelator IRs
here
