0 to 127
The Ambience algorithm parameter controls the level of the reverberant part of the decay. This parameter is unique to the Ambience algorithm. You can almost think of this algorithm in two sections, the early part of the sound and the reverb tail.
When you're at 0, not all of the early reflections will be audible to you, and the sound itself will fade out abruptly once those later early reflections disappear.
If you want a natural blend of early and late reflections, set this parameter to about 70.