Bo Holm-Rasmussen, Heidi-Maria Lehtonen, and Vesa Välimäki
A New Reverberator Based on Variable Sparsity Convolution
Companion page for a paper submitted for the 16th International Conference on Digital Audio Effects (DAFx-13), Maynooth, Ireland, September 2-6, 2013
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.
The reference impulse response (zip-file containing s1_r3_o.wav) measured from the concert hall in Pori, Finland, available from its original webpage, the replicated impulse response, and the abstract reverb effect impulse response.
Updated on Monday June 17, 2013