Scattering in Feedback Delay Networks
This work addresses a domain-specific problem in artificial reverberation and decorrelation for audio processing, presenting an incremental improvement over prior methods.
The authors tackled the challenge of increasing echo density in feedback delay networks (FDNs) without sacrificing computational efficiency by generalizing feedback matrices to arbitrary lossless filter feedback matrices (FFMs), specifically proposing a velvet feedback matrix that creates dense impulse responses at minimal cost. They demonstrated effectiveness in terms of echo density and modal distribution.
Feedback delay networks (FDNs) are recursive filters, which are widely used for artificial reverberation and decorrelation. One central challenge in the design of FDNs is the generation of sufficient echo density in the impulse response without compromising the computational efficiency. In a previous contribution, we have demonstrated that the echo density of an FDN can be increased by introducing so-called delay feedback matrices where each matrix entry is a scalar gain and a delay. In this contribution, we generalize the feedback matrix to arbitrary lossless filter feedback matrices (FFMs). As a special case, we propose the velvet feedback matrix, which can create dense impulse responses at a minimal computational cost. Further, FFMs can be used to emulate the scattering effects of non-specular reflections. We demonstrate the effectiveness of FFMs in terms of echo density and modal distribution.