Damping Filters for Reverberation Delay LinesIn an FDN, such as the one shown in Fig.3.10, delays appear in long delay-line chains . Therefore, the filter needed at the output (or input) of the th delay line is (replace by in Fig.3.10).4.15 However, because is so close to in magnitude, and because it varies so weakly across the frequency axis, we can design a much lower-order filter that provides the desired attenuation versus frequency to within psychoacoustic resolution. In fact, perfectly nice reverberators can be designed in which is merely first order for each [314,217].
First-Order Delay-Filter Design
Conformal Map Interpretation of Damping Substitution