Comb Filter Decay Rate

The response decays exponentially as determined by the loop time and gain factor $g$.

Values of $g$ nearest 1 yield the longest decay times.

To obtain a desired decay time, $g$ may be approximated by

$$g = 0.001^{\tau/T}$$

where

$$\tau =$$ the loop time

$$T60 =$$ the time to decay by 60dB

and 0.001 is the level of the signal at 60dB down.

Figure 23: Comb filter impulse responses with a changing the decay rate.