Wwise SDK 2019.1.11

The maximum number of edges that the sound can diffract around between the emitter and the listener, or the emitter and a single portal. Applies only to geometric diffraction, and not to sound propagation through rooms and portals. Setting diffractionMaxEdges to 0 effectively disables geometric diffraction for this sound emitter. When using geometric diffraction, the default value is a good starting point.

AkSpatialAudio.h の 175 行目に定義があります。