Multi-Ripple Loss filter for Waveguide Piano synthesis

The multi-ripple filter is a new approach to model losses in digital waveguide synthesis. Stringed musical instruments produce decaying sounds due to physical losses, which need to be modeled. In digital waveguide string model, the losses are modeled with a loss filter. Another function for the loss filter is that it is needed to make the model stable. In piano synthesis, a high-order loss filter is needed, because of the large variation of partial decay times, which correlate to the audible sound. The multiripple loss filter is a combination of a single one-pole IIR filter and an arbitrary-order sparse FIR filter. It is able to powerfully model the differences in the partial decay rates, especially with higher orders. The multiripple loss filter can be efficiently designed by using the frequency-sampling method. Finally, a comparison between the multi-ripple loss filter and some common filters is presented showing that the multi-ripple loss filter performs well with a small computational cost.