This article provides guidelines for placing microphones in Ray-acoustic model
In Ray-acoustic analysis, it is not possible to reconstruct the acoustic pressure accurately exactly on the model boundary surfaces due to theoretical limitations. Microphones should be positioned at least 2-10x the model tolerance (Geometrical Tolerance in the Advanced Options of the Solver Parameters). In this distance interval, special techniques should be applied to make sure that only the direct incident field is captured by the microphones. Unfortunately, these techniques are not currently supported by Simcenter 3D. For microphones that are more than 10x the Geometrical Tolerance from the boundaries, no issues are expected, and good accuracy should be obtained.