Q: I get negative values of SPL in places, where I would expect sound pressure to be noticeable?

A: Check 3DopenGL and ray tracing if the point-, line- or surface- sources are inside the room and transmitting most of the sound energy into the room. Make also a 3DopenGL check of the receivers. If using a grid map it is possible to exclude receivers outside of the room from being displayed in 3DGrid when the chosen parameter is over or under a selected range. This is set in the Options/Program setup/Grid colours.