Signal-dependent Nonlinearities for Physical Models Using Time-varying Fractional Delay Filters
Vesa Välimäki, Tero Tolonen, Matti Karjalainen · 1998
This paper discusses the use of nonlinear filters that are based on linear digital filters with input-signal-dependent coefficients in the context of digital waveguide synthesis models. It is proposed that the practical uses of such filters in music synthesis may be generalized to a time-varying fractional delay (TVFD) filter with signal-dependent coeffi-cients. Three different cases are outlined: 1) simulation of a pressure-dependent wave propagation speed in a wind instrument bore, 2) nonlinear termination of a vibrating string, and 3) a tension-dependent variable speed of trans-verse vibrations on a string. Implementation structures for TVFD filters based on FIR filters are suggested. 1