A New Reverberator Based on Variable Sparsity Convolution

Bo Holm-Rasmussen, Heidi-Maria Lehtonen, Vesa Välimäki

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


An efficient algorithm approximating the late part of room reverberation is proposed. The algorithm partitions the impulse response tail into variable-length segments and replaces them with a set of sparse FIR filters and lowpass filters, cascaded with several Schroeder allpass filters. The sparse FIR filter coefficients are selected from a velvet noise sequence, which consists of ones, minus ones, and zeros only. In this application, it is sufficient perceptually to use very sparse velvet noise sequences having only about 0.1 to 0.2% non-zero elements, with increasing sparsity along the impulse response. The algorithm yields a parametric approximation of the late part of the impulse response, which is more than 100 times more efficient computationally than the direct convolution. The computational load of the proposed algorithm is comparable to that of FFT-based partitioned convolution techniques, but with nearly half the memory usage. The main advantage of the new reverberator is the flexible parameterization.
Original languageEnglish
Title of host publicationProceedings of the 16th International Conference on Digital Audio Effects (DAFx-13)
Number of pages7
Publication date2013
Publication statusPublished - 2013
Event16th International Conference on Digital Audio Effects (DAFx-13) - Maynooth, Ireland
Duration: 2 Sep 20135 Sep 2013


Conference16th International Conference on Digital Audio Effects (DAFx-13)
Internet address

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