Velvet-Noise Feedback Delay Network
Artificial reverberation is an audio effect used to simulate the acoustics of a space while controlling its aesthetics, particularly on sounds
recorded in a dry studio environment. Delay-based methods are
a family of artificial reverberators using recirculating delay lines
to create this effect.
The feedback delay network is a popular
delay-based reverberator providing a comprehensive framework
for parametric reverberation by formalizing the recirculation of
a set of interconnected delay lines. However, one known limitation of this algorithm is the initial slow build-up of echoes, which
can sound unrealistic, and overcoming this problem often requires
adding more delay lines to the network. In this paper, we study the
effect of adding velvet-noise filters, which have random sparse coefficients, at the input and output branches of the reverberator. The
goal is to increase the echo density while minimizing the spectral coloration. We compare different variations of velvet-noise
filtering and show their benefits. We demonstrate that with velvet
noise, the echo density of a conventional feedback delay network
can be exceeded using half the number of delay lines and saving
over 50% of computing operations in a practical configuration using low-order attenuation filters.