Scattering in Feedback Delay Networks

Sebastian J. Schlecht*, Emanuel A.P. Habets

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)
106 Downloads (Pure)


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.

Original languageEnglish
Article number9113451
Pages (from-to)1915-1924
Number of pages10
JournalIEEE/ACM Transactions on Audio Speech and Language Processing
Publication statusPublished - 10 Jun 2020
MoE publication typeA1 Journal article-refereed


  • artificial reverberation
  • echo density
  • Feedback delay network
  • paraunitary matrices
  • scattering


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