Achieving Desired Reverberation Times

To set the reverberation time, we need to move the poles of the lossless prototype slightly inside the unit circle.

We want the to move high-frequency poles farther in than low-frequency poles.

Basic substitution:

$$z^{-1}\leftarrow G(z)z^{-1}$$

where $G(z)$ a lowpass filter satisfying $\left\vert G(e^{j\omega T})\right\vert\leq 1$ for all $\omega$ .

• $G(z)$ = per-sample filter in the propagation medium
  First applied to complete reverberators by Jot
• Jot suggests

  All pole radii in the reverberator should vary smoothly with frequency.

  Otherwise, late decay will be dominated by largest pole(s)